Yea it used to be a sticker, and that was nice for the reason you mention above. However, that meant your pass was only good for one car and if that car was in the shop or you went with your buddy you had to pay (con). Then they switched to a card that they sold every year that was a different color (similar to your car registration sticker). That system was my favorite because it wasn't stuck to the vehicle, but could be thrown on the dash or flashed at the ranger. The con with the color coded card was it was calendar year only, so the later in the year you bought it the more expensive per use (though it dropped to half price in August). Now they have the yearly pass that you can buy anytime during the year. I guess it's nice because you don't have to worry about buying it in December, but the cons are somewhat annoying: the ranger has to scan it (takes longer), I forget when my card expires, and I have to go to the kiosk and be frustrated because half the time the damn machines don't read the card or don't work at all. In that case I throw the pass on the dash with a note "THE CARD READER DID NOT WORK!". Haven't been ticketed once.