You had the headquarters of the far-reaching Hutt syndicate there
I think
The Clone Wars showed that the heart of the Hutt syndicate was on Nal Hutta. Jabba was just one member who chose to use an abandoned monastery on Tatooine as his base, much as Ziro operated out of the Coruscant underworld and other Hutts were based elsewhere.
as well as the Pod Racing championship, featuring competitors from all over the galaxy.
The Boonta Eve Classic was held on Tatooine because Jabba was the one who ran it. So it's not a coincidence. And podracing doesn't really strike me like a major sport; it's so insanely dangerous that I question if it's even legal in the more civilized parts of the galaxy. It is run by a crime lord, after all.
The Tantive IV getting caught over Tatooine was never meant to be a coincidence, it was there very specifically to pick-up Obi-Wan. Neither was the idea that Anakin had family there or that Vader had a connection even before they were both the same person. Remember, Vader was always said to be a former pupil of Kenobi.
These aren't coincidences, they're simple cause and effect.
Yup. Let's see if I've got this... Anakin came from Tatooine and had family there, so Obi-Wan, Yoda, and Bail chose to leave Luke in the care of said family. Obi-Wan stayed to watch over Luke. Bail knew he was there, so when the Alliance learned of the Death Star, he tasked Leia with going to Tatooine to make contact. The
Tantive IV got diverted to Scarif for the battle and ended up in possession of the plans, and Leia proceeded to try to deliver them to Obi-Wan. Vader tracked her down and intercepted her just before she could complete her mission.
And Shmi and Anakin only ended up on Tatooine in the first place because their original owner, Gardulla the Hutt, lost them in a bet to Watto. Since Watto was an inveterate gambler, I'd imagine he moved to Tatooine because of the podraces held there.
So ultimately, the reason all these things (not to mention Han and Chewie) converged on Tatooine is because it's where Jabba was based. Influential fellow.