Voting is analogous to taxes and should be legally enforced as such.

Well, informed voting is, but how do you reliably check if somebody was well-informed as they voted, to legally enforce it?

the public service of attending a voting booth and scribbling something arbitrary that may or may not be a vote on a piece of paper should be compulsory.

Why? I fail to seem any gains from that. Neither do I see any major empirical differences between countries with compulsory voting and countries without.

I agree that voting is a Tragedy of the Commons - but in the exact opposite way to how you frame it. Because people don't fully internalise the costs and benefits of their votes, but value self-expression, (1) it is very cheap for the ill-informed to use their votes to signal expressively, and (2) there is little incentive to become a well-informed voter. For a given level of political ignorance, we get far too much voting.

To my mind, voting is analagous to pollution and should be taxed as such.

Why? Assuming I vote randomly all I'm doing is increasing the noise to signal ratio. If everyone you force to do it votes randomly then it'll average out.