Agreed. But, the OP wasn’t asking about tax implications, he was asking about commuting and these folks are living in and commuting from Ireland, Sweden, etc..
I don’t think he cares where they live “on paper”.

If he wants to do the same he will, less he increase his tax percentage by 20-30%.

If anyone is thinking of living in Europe (or internationally in general) and especially if you have multi-nationalities, consider the following:

If you live in Europe as a European citizen (read: reside/qualify for a “tax home” status over there), you will be subject to Euro income taxes, healthcare obligations, and a whole slew of other gotchas. Further, not being a US resident while working in the US for a US company complicates a lot of things like our pension, DC and 401K plans, insurance benefits etc; eg., the tax shelter of these plans doesn’t necessarily exist in the eyes of a foreign tax authority; its all dépendant on the tax treaty between countries and note that those treaties are usually only at a federal level and not necessarily with lower levels of govts (think of an EU equivalent of a state level govt / income tax). Also, few if any US bank accounts or credit cards etc., will allow active participation to non US residents; foreign resident investments in US brokerages gets really complicated really quickly. Last, UPS will only direct deposit to a US bank and will apparently only accept a US address in their HR system (I’m not clear on the exact details of this). Depositing a US payroll check into a foreign account also gets interesting especially with currency conversion hits and fees (and how would one even get that check when UPS sends it to US address on file?). Even moving to Europe and paying their taxes as a resident is really messy and ends up wasting a good chunk of money. Eg, you pay for health care over there but still required to hold the one through UPS = double paying. I’m pretty confident these guys are living in the states and just visiting their family and hometowns on a frequency that our profession and travel benefits allow. If they don’t have EU passports then this is all a moot point as they would have no rights to residency over there.

Sorry OP, I just assumed you had EU citizenship. If you don’t hold a EU passport the only easy and practical option is to enter Germany on a visitor visa. There might be options for up to 6 months or longer at a time and all you’d have to do is exit and re-Enter at the end of it. Same for the family if applicable. That part is easy. Things will start to get problematic when you try to open bank accounts, rent a place (security deposits/monthly payments), setting up utilities, cell phone bills, kids schools, buying a car and registering it/ ins, etc. Based on the limited research I’ve done, I think the simplest way is to buy property over there as a vacation home. It helps with a bunch of the issues above and may give you rights to longer stays (but beware of non-citizen residency issues). Expat forums and expat retirement forums, country specific, have lots of good info and highlight things you may not think of. Otherwise, perhaps you could try for some sort of work visa or even one through your spouse?? Any extended family living over there? You could go through them for solutions to a lot of these issues.

If you are already over there and have established a little seniority built up, your best bet for trips by far would be on the Z. There aren’t that many Z trips with DH/CML to and from Europe (which obviously goes senior) but lots of intra Europe flying with weekends off in CGN and lots of CGN stuff in general. I haven’t kept close tabs on it but the whale is flying through CGN more and more taking over the old MD stuff but then you have the ANC commute to factor in. The MD probably won’t be much of a CGN player by the time you get here. If you can’t hold any of the above you could bid a domestic fleet and just commute. Not too terrible if you live close to CGN. It’s really a question of seniority at the end of the day.

Per previous post, you can drop UPS health bennies if you can prove you are otherwise covered.

Hey FDX guy here - what are your layover cities in the E.U.? See a lot of overlap on our destinations over there

Cdg
Hel
Arn
Ema
Stn
Vie
Bud
Cia
Mad
Vlc
Osl
Off the top of my head