I've done a fait bit of prep for tarmac over the years so we set up with laser and try respect the falls needed if you were tarmacing even if its just gravel, its pretty good practice in general and I figure that if at a later date they want to tarmac then prep wise its a relatively simple reprofile and compact etc.
Where its not possible, like the little job in photos then I discuss with client the issues with falls and what is doable, in that particular job the fence/gate and garage were too low with respect to the road so if he still wanted to get his van in there then it was what it was falls wise, we discussed drainage etc and came to the best compromise within his budget/requirements, also we were working over some old footings that he didn't want taking out so we had to be content with a bit of crossfall in one area , I think its just a case of the customer understanding you had given the job due consideration in respect to falls and drainage.
Regarding flatness then we work to the laser (idig sometimes nowadays) and tbh its usually pretty decent

If you can get a nice constant grade across a job in both axis then it usually looks the part, but not always possible.
Regarding depths, I have my usual ideas for various aggregates and adjust if needed but guarantee it won't turn to s**t.