"What should I reasonably expect to be done here?"

The tub and floors needed to be leveled or at least the options discussed with you prior to the install of the new tub. The floor should have been leveled for the new tub install period. The sliding doors have to installed level and square so on that part they are correct. I would not expect to see a 3/4" gap under my new doors between my new doors and my new tub. What else is new? Who did this work? Pictures?

3/4" is absolutely not acceptable and the reason they are saying it's fine is because the GC screwed up and figured you'd just accept it. I hope you didn't finish paying him/her

If the tub didn't drain and you had this problem, you'd have a tear-out case; you probably don't. Take a shower and see if it leaks, please.

Yes, I want to be fair and do realize that mistakes happen. And, yes, I could take showers and see if water leaks out through gap of bottom of glass door and tub. And if no leakage happens, then pay GC and deal with the look of the difference between the gap in front of tub to back of tub? If no shower glass door had been installed, I would put up shower curtain. It is quite frustrating that glass installer did not tell me before first drill went into my brand new tub that your tub is not level.

If it doesn’t leak, a strip of solid surface matches to the tub as a kind of molding might work. Pictures would tell the story here. We are all flying blind.