Why is tornado alley so famous when more tornados happen in the south than places like Kansas and Oklahoma?

I don't know why nobody seems to think of Florida when it comes to tornadoes. It ranks third in the number of tornadoes that occur of all the states.

...Oklahoma IS in the South. So are parts of Tornado Alley.

And per square mile, Oklahoma most certainly DOES hold the world record for the greatest number of significant tornadoes (Florida wins the per-square-mile count overall, but only if you generalize the term "tornado" to include non-meso spouts). The ONLY reason Texas' number is higher is because it's the biggest state in the contiguous US. It takes something like 16 hours to traverse its widest part.

That’s very incorrect.  There is evidence that tornadoes are on the rise in the American South, in the weather community it is called “Dixie Alley,” and tornados do seem to stay on the ground longer.  However, let’s dig a bit deeper to see why it may seem Dixie Alley has more tornadoes than the more notorious Tornado Alley. To get straight to the point from the get go, tornado alley does have many more tornadoes than Dixie alley does.  However, the Deep South of the US is much more heavily populated than the southern plains states.  Even in a region such as tornado alley where tornados are so numerous your odds of ever being hit by a tornado are near next to nothing.  The larger a population area is the more likely it is to be involved with a tornado.  Take Oklahoma City for example, it’s one of the most spread out cities in the US even though it’s metro population is around 1.4 million, it has been struck more often than any other US city due to how spread out it is.  So if there are more people in the south someone’s odds of being in a tornado are increased.  Why is this needed to be understood for the number of reported tornadoes?  Because to this day meteorologists still mainly rely on a human spotting and reporting a tornado.  As the population areas of the south continue to grow you have more people calling to report tornadoes that more than likely used to go unreported.  Here’s the other catch.  Doppler radars are becoming more advanced and sometimes now they can detect motion.  In the south it is very hilly so hundreds of tornadoes more than likely used to go unreported simply due to not being able to see them but now because of Doppler radars being able to detect rotation they can be more easily documented.  This is the reverse of tornado alley where it is generally flat and people can see tornadoes from miles away.  This within itself can explain why the Deep South seems to be having more tornadoes when they’re not, it’s simply better technology.  Something else to look at is how houses are built.  Homes in tornado alley are generally built to a higher standard with knowing their odds of a tornado are high while places in the south home standards are lower including more people living in modular homes.  Why is this important?  Because it gives an illusion when the south has a tornado that it’s more destructive than when the plains states do when they’re not, it’s simply better building standards.  Then there’s the actual tornado seasons.  Tornado season in the Deep South is earlier in the year and can reach its peak around March and early April, while tornado alley peaks in May.  This is important because for 2 months you’ll only hear about the Deep South having tornadoes when they have always had a tornado season earlier in the year, it isn’t because tornado alley isn’t having tornadoes it simply isn’t their time of the year yet.  Now with this there is some, and I use some very lightly, that there is an increase in tornadoes in the Deep South due in part to climate change.  I am an individual that argues against this.  Why?  They aren’t having more tornadoes, and tornado alley isn’t having less.  While the Deep South is alerting citizens to rotation on radar more often as technology has advanced, tornado alley from the high frequency of tornadoes, has a stricter standard on when to send alerts and instead of doing multi county warnings like they used to most now only alert citizens in the immediate path cutting down on false alerts while also creating the illusion there are less tornadoes.  To wrap everything up, Dixie Alley is a tornado alley within itself, but even if they are having more tornadoes tornado alley still outdoes Dixie Alley.  Tornado Alley has also always had some years where they almost have no tornadoes reported, just as Dixie Alley.  This has nothing to do with the number of reported tornadoes decreasing it’s simply just part of how their sequence has always went.  Outbreaks then nothing.  There are several news reports from people that have no background in meteorology reporting on the supposed increase of tornadoes in the south but most of these articles are written to catch readers attentions, especially those who live in the south.  They often fail to mention why there would be an increase in tornadoes and simply say climate change while leaving out technology and how Doppler radars can now detect rotation when due to how hilly parts of the south are tornadoes used to be nearly impossible to see.  I do believe in climate change, but I do believe Dixie Alley having more tornadoes is erroneous when there are simple explanations.

Only if you are referring to "the south" as one state.  Because Oklahoma is such a large state, there are still more there than in any single state along the south.  

The climate has changed.