I wish this (and more like this) was posted in main.
(ducks before accusations of misusing "isomorphic")
Old joke:
Q: Are these two objects isomorphic?
A: The first one is, but the second one isn't.
There are absolutely differences in the perceived value of the same degree from different institutions. I've also heard of deparments that have received complaints from businesses that the quality of graduates with a certain degree has dropped due to grade inflation. That has led to a painful period of lower results as they try to correct the problem.
If the lecturer happens to be a postdoc (which is not unheard of in a final year course, for instance) then they are also likely to do the marking. I agree that exam marking is unlikely to be farmed out to postdocs who are otherwise not involved with the course.
The draft examination papers are sent to the external examiners, who make comments as they deem appropriate. These might, for example, be "this question is too hard" or "this question is not clear". The final approved exams are then taken by the students and marked by the lecturers who set them. The external examiners then return during the moderation process, helping to decide where the boundaries for various classifications should be set.
Side note for those who might not have come across him before: Kevin Warwick is a Professor of Cybernetics who, among other things, has communicated with his wife through electrical cables attached directly to nerves in their forearms.
The other videos I've sampled from that channel have also been good.
The UK university system is of course very different from that of the US, but there's a similar effect. Tuition fees are roughly constant, but Oxford and Cambridge have generous bursaries for students from lower income families and subsidised housing, so are generally cheaper than the less prestigious (and less wealthy) alternatives.
I wish this were posted in main.