In my area, UPS has never appealed to young employees. When I reached my tenth anniversary, I was both one of the most senior employees and youngest employees (I was 27) in my facility. Beginning in 2008, when jobs became scarce, there was a youth injection but now that entry-level jobs are becoming more plentiful, few youth are hiring in. Nonetheless, as UPS is self-insured, offering an alternative such as system-wide tuition reimbursement, would likely be more costly. And the youngsters are pivotal in keeping costs down in areas where UPS forks over cash to the Teamsters to purchase plans.
From 2000-2005 (at least), turn over was very high -- both among PT and FT (I live in the heart of suburb sprawl, and they were adding routes frequently). In fact, we had a very large number of PT that, although employed with UPS for a number of years, actually worked for a temp agency earning higher wages in the short-term. Once again, turn over has been high... if UPS were to eliminate benefits, how attractive would these jobs be? Get up at 3AM, work 3 hours for $8.50 an hour, have immense pressure for productivity & perfection - while paying union dues.
UPS could keep benefits for new hires for many years, but become more creative: offer the same menu of plans as management & non-union (including the same premiums). Dilute benefits for current employees ($10 office visit goes to $20, which IS the national average, etc.) Incorporate lower-cost alternatives such as pharmacy-style clinics (Minute Clinic, etc.) and waive co-pays. Offer a level of reimbursement for OTC drugs -- if employees were able to medicine like (generic) Clariton for free, it'd discourage more costly office visits.
Just my two cents...