Neither did previous laws about overtime pay and healthcare... None of this started with Obama. The "gold standard" of 78 hours for a two week paycheck so no benefits needed to be provided has been going on for over 30 years that I know of and I'm sure it's been much longer than that.
With exception to some union rules there is not much difference between a 40 hr. Full time employee and a 39 hour pt timer. There is no overtime involved.
with a good union, you get time and a half for anything over your regular 8 hours, in any 24 hour period, each and every day it occurs. and double time and a half for working your assigned rest days.
Unions once upon a time were great for looking after you, now they work for the company's..in UK anyhow.