^As someone who has recruited into the hospitality sector, I do tend to bypass those who are over qualified as its usually someone who is marking time until the dream job comes along.
I would imagine it is similar in the supermarket sector.
And right now, given that I have been looking for a new job for over a year, I would suggest that YABU for saying any reason that someone cant get a job apart from "there aren't enough jobs out there right now thanks to redundancies and lay offs".
And nice that you can afford to go part time, the rest of us didnt stack up the cash in a nicely paid career and then smugly live off it later......^
OP, whether you realised or not your original post came across as the above.
There is a certain hypocrisy in what you are saying.
First you seem to have had a job and career matching your qualifications and were able to choose to downgrade your jobs because it suited you.
Secondly you were able to afford to downgrade your position due to savings, investments or other money that you had. This isnt possible for everyone especially young people starting out on a career that may have families.
So, yes you are being unreasonable.