I don't understand what kind of mental gymnastics it takes for policymakers to impede paying taxes. How absurd is it that the government would rather make it difficult for its citizens to give it money!? ( ͠° ͟ʖ ͡°)
There is absolutely no problem to give money to the government. Filing in taxes with extra is fast and easy. Filing for the exact sum is hard.
There is a self-aware viewpoint among the libertarian right that if the government makes it a pain to pay taxes, then people will hate doing taxes, which will in turn direct them to push for a smaller government. It's called "starve the beast."