SF Residential Parking Permits

Why do companies make it so impossibly hard to remove parking permits from our car's bumpers?

I appreciate that I live in a neighborhood that requires a residential parking permit for all resident cars. It prevents the neighborhood from being flooded by cars from out of our area from parking in our neighborhood for an extended amount of time. This is helpful in popular shopping/eating neighborhoods (like Castro Street) and also for neighborhoods that are located near public transportation centers. (again, the MUNI line at Castro x Market Street)

San Francisco requires that we place our parking permits on the bottom left bumper of our car.
That's fine, although not terribly attractive on any car that I've ever seen.

They also make it impossible to peel the permit off in any less than 20 pieces. (and really, you're lucky if you can manage to get it off in 20 pieces!) I suppose It's designed this way so that bad people cannot swipe your permit off of your car.

This is all fine and dandy, but it's a pain in my tuckuss when it comes time to renew the permit each year.

I just spent the last hour painstakingly peeling off the permit from last year from my bumper. I used the old technique of a razor blade, and Goo-Off. It worked fine, in the end, but really, what a pain! (and I was pretty upset when my razor blade slipped and scratched the paint in my bumper) I could have just stuck this year's permit on top of last year's (as Dick did) but I don't like the idea of years and years of permit build-up on my little car's rear end. I plan to have my car for several years, so I know that eventually I'll be stuck peeling off years of sticker build-up.

So now that my bumper is nice and clean, I've decided to live on the edge:
I've taped my permit to the back window of my car, on the bottom left side. I've seen several cars throughout the city that have done the same thing, so I'm going to give it a shot. Technically, I could totally get ticketed for this because I haven't put the permit in the proper place. I have a hatch-back car though, so it would be hard for the meter-reader person to not notice it. That's not to say that they won't still issue me a ticket, though.

anyone out there have any experience with this?
I just might cave within the first few hours and put the permit permanently on my car's rear bumper again.

update
I just spoke with one of my friendly neighborhood meter-readers, and she said that as long as the parking permit is visible, then it should be okay. :)