When I was a lot man, I became very good at removing window stickers as part of the final cleanup before delivery. I'd either leave them on the dash or put them in the glove box (I forget which, it's been 38 years).
The amount of glue they used varied widely from car to car. There were some that were completely coated with it--start a corner with a razor blade and they'd peel right off, leaving no paper behind. Others were really on there and I'd have to scrape veeeerrrrryyyy carefully to get them off intact.

I think I pulled my own on the '86 Charger when I got home. When I bought the Daytona five years later, the salesman didn't want to let me leave with it still on the window--said it was a liability issue because it blocked a big chunk of the passenger window. I may have persuaded him to let me remove it myself at the dealer. Both of those still had the sticker in the glove box when I let them go.

I like the way they do it now, with the backing that only has adhesive where it touches the glass so the sticker itself comes off clean.