> If many American companies had their way, the average
> employee would be a part-timer.
I think the 'many' is probably overstated, but I think a bigger problem is that the standardized 40hr work week has spawned a different problem: if most people work 9-5/M-F, when do those people get to do their commerce? That's right: evenings and weekends. So someone has to have those jobs. For scheduling purposes, I bet a lot of employers would rather their workers worked *more* -- like 60 hours. But since paying someone for 60 hours is the same as paying two people for 40 hours each, it makes more sense to pay 2 people for 30 hours each.
In the case of UPS, the job is literally: do work when there are packages, don't do work when there aren't. There are plenty of other jobs where this is true (firefighters and doctors spring to mind, but also pilots/flight attendants, and teachers who work 9 months/year). You can't have overnight delivery services without clusters of people doing that work in that way. Which will it be then?
On the other hand, I've noticed that a lot of "full-time" jobs only really require 20-25 hrs/week of actual work, which leads to people spending time 'looking busy' and dragging things out so that they can justify it (introducing self-fulfilling inefficiency). I'm not sure how that happens except to believe that the overhead involved with saying: "okay, you work from 10-3 each day; and you are from 8-12" isn't worth it.
> If a lot of companies had their way, the average work
> week for their employee would be 20 hrs.
If you mean because then they wouldn't have to pay for benefits, I think you're overstating again; scheduling twice as many people is harder, and handoffs between shifts are always unproductive. There's a certain amount of overhead that's per-employee (think about things like training), and I'd bet that most employers would rather not double-up on those. Quality goes down, efficiency goes down, headaches go up.
I think a lot of the people who say "I can't get enough hours" are in the positions that have such bursty behavior. A simple example: restaurants that are open all day have rushes at (nominal) meal times that can require 3x the labor of the non-rush hours. If you want a $9 hamburger, all those people can work "full time" ... but if not, some will have to work exclusively at the busy times.
If I were an employer that had a significant part-time workforce, I'd be happy to pay for benefits on an _exact_ sliding scale; your group health premium is $X and you worked 123.6 hours this month that had 23 days [184 "full time hours"] so I'll pay 67.173% of it, or something like that. It's the edge-conditions (20 hours gets you half benefits, 35.5 gets you full) that introduces all the inefficiency. We've got computers, they do math pretty well, why not use them?
/jordan