I'm not suggesting that I would, nor that UPS is, charging fees merely as a scheme to make money. I'm sorry if it came across that way.
UPS is one of the most data rich companies in the world. I can assure you that they know to the nth of a penny how much it costs to make a rural residential delivery compared to an urban one, etc, etc. However, unless they were to analyze every single address there is, there is no way to make it "fair" for every single customer (my definition of "fair" is to charge the customer based on what it costs). I'm sure that the person paying the extra fees doesn't think it's "fair" to have to pay extra, and that UPS should just raise their prices (a little bit) to cover it. However, that wouldn't be "fair" to the customers to whom it costs less to deliver to, as they would be subsidizing the more expensive ones.
I've never run a frame shop so I can't give you a specific examples, but I'm sure there must be some things that you have rates for that change dependant on what it is you're doing (I'm just guessing, but say fitting - do you always charge the same amount, or are there variations or exceptions?). You could just set the rate to the average and make the same total money in the end (actually, you may not, but that's another whole can of worms), but would that be "fair"?
The bottom line is that UPS is responsible for making its shareholders a profit. One thing they don't want to do is make their biggest and most important customers (urban commercial) unhappy, so they try to make sure that they are "fair" to them. The fact that some of the smaller "less important" customers become unhappy is unfortunate, but "you can't please all the people all the time".
I can't believe that I'm supporting UPS, because these extra fees tick me off, but when I look at it from a business standpoint (as if it were mine) I think it's the right thing to do.
One final note - the only thing you may be able to convince UPS of is whether you're commercial, not residential. And in fact, that seems to vary from time to time. Peter, I don't know if you see your UPS bills, but they "correct" the charges if you don't enter it correctly. I've changed some of our customers back and forth so many times based on UPS's "corrections" that I think their heads must be spinning. The delivery area surcharge is based entirely on zip code - not much you can do about that.