My old Barber, Tom, was getting ready for retirement ... and he had a small farm he was planning to "develop" as his project.
He got a small bulldozer at an equipment auction, and he had a ball moving dirt here and there ... for a while.
Then he rolled the dozer. As bad as a mower rolling can be, a dozer rolling can be worse. It killed him . Literally.
One of my best friends, a Brit who'd settled in the USA and was a Professor of Mechanical Engineering at a major university, rolled his mower once, and was knee capped. His mobility was never the same. You'd think that a Professor of Mechanical Engineering would value safety features ... and I think he does today.
Sigh....
I am glad that your incident was no worse and I look forward to your complete recovery.
FWIW, the roll bar and the seatbelt are a good idea, but you've got to use them. I've got a commercial mower powered by a water cooled 750cc Kawasaki Industrial V-Twin (the only V-Twin I've ever owned that I really liked). There's an interlock to shut down the engine if pressure on the seat is reduced. Seat belt and roll bar too. It seems pretty stable, but on a significant slope, none of them can be trusted.
Be careful ... it's a jungle out there.