I don't understand how Prizeo complies with relevant contest related law. You get entries in proportion to the size of your donation, but apparently contributing does not improve your chances of winning. This seems to be a direct contradiction.

From the contest rules:

The winner will be chosen at random using Prizeo's certified random number generator. No payment or contribution is necessary to enter or win. Contributing will not improve the chances of winning. The contest is subject to Prizeo's Terms and Conditions. The prize is non-transferable.