Re: I dunno but
"Take off from a barge, ok.... but why try to land on a barge? Theres all that desert and empty land you could use as it normally doesnt go up and down a lot."
The answer is a combination of launch constraints and first stage performance.
Launch constraints (like location of the rocket company and import/export rules) have required a US launch pad.
Launch constraints like, "Have a big, open area where rocket confetti has a small risk of hitting Americans" discourages inland launches. The US's western deserts are big, open, and lightly populated compared to Europe, but they ain't Kazakhastan or Siberia. Note Vandenberg on the US West Coast is pretty limited in its launch directions, mostly over-the-pole shots, because the US doesn't like rockets flying inland. So, east coast launchers are preferable.
Launch constraints like "try to be reasonably far south to exploit equatorial spin velocity" on top of the above constraints leads to Texan, Floridian, or Puerto Rican launch sites. High inclination shots from Texas (e.g., to the ISS) run into issues that rockets will pass over the US interior, so Florida and Puerto Rico have been on the short list of launch sites, with northerly Virginia sites sometimes used to capture exploding, Russian-powered rocket debris. Florida has an advantage in rocket infrastructure and aerospace lobbying experience over Puerto Rico, so flights end up launching from there.
The next issue is rocket performance. The first stages of rockets generally do not get very far from the coast. After heaving second stages above the atmosphere and through that first few thousands of miles per hour, first stages generally can only make it 50 to 300 miles from Florida.
This is well short of any landing in the Sahara desert or Spain (as the shuttle considered for certain, brief parts of its ascent). Generally - until SpaceX's Falcon 9 v1.1 - the first stages were designed to be out of fuel by the time they dropped away, so a return-to-launch site was strictly an insane option for US shuttle emergencies. Really, look up a shuttle RTLS abort, flying mach 5 backwards. Awesome stuff, but not for the faint of heart.
Anyway, the Falcon 9 v1.1 first stage is running light on fuel by stage separation so allowing aerodynamic drag to perform a fuel-saving braking maneuver and then using a little remaining rocket fuel is easiest. Given launch constraints and performance constraints, that means the first stage is going to be settling in the ocean some hundreds of miles off the coast of Florida. You need a barge, or a rocket-sized swimming suit.
Eventually SpaceX wants to improve performance until landing back at Florida is an option, but - as noted by other commenters - they'd prefer to do that after the crashing and exploding bugs are worked out. There are more people in Florida than on the SpaceX barges.
Biting the hand that feeds IT
