[Serenissima Venezia]

I don't believe that a physicist/engineer/mathematician with a PhD would make $40K a year.

A newly graduated engineer with no experience should start off making more than that and mathematicians/physicists probably around $40K (joboutlook.com). An engineer with a PE averages $100K a year. So I believe your numbers aren't quite right.

I imagine there are the occasional people who have done through a lot of schooling and still couldn't be the job the wanted, but I don't think it's most of the graduates. I did work with a teacher with a biomedical EE MS degree who couldn't get a job in his field, but his field is pretty specialized. And he had some odd mannerisms and a very arrogant attitude, which may have put off some employers. He is, however, making an excellent teacher (but not making much money.)

[Feldkurat_Katz]

I don't believe that a physicist/engineer/mathematician with a PhD would make $40K a year.

Frankly, it doesn't matter whether you believe it or not.

From Stanford Postdoc Survey

"$35,709 Average starting gross annual salary / stipend
$40,398 Average current gross annual salary / stipend (all PDs)"

It's even worse than I thought - they start at $36k and reach $40k later.