The entire SSI/SSDI system is fucked. It's arbitrary and unnecessarily complex. Linking disability benefits to time worked is also cruel and arbitrary to younger workers who become disabled. And especially to people who never have the chance to build a work history at all. Then the idea that it has to be capped to an even outcome instead of a livable floor plus medical expenses...

That last part might just be why the younger people get paid more. They have less assets that count against the monthly pay.

But there is one thing SSI/SSDI have in common. The pay drops in step with money earned. So if you go get a job then you're not going to get much of an SSI check, if any at all. And SSDI can be outright revoked for working.