Here's the other practical test, related to voting and possible sins of omission/laziness: How much effort does it cost one to vote? How much potential evil could happen if you DON'T vote? The cost/benefits are amazing.
You search the internet to find one of the many, free family/pro-life organizations that provide you a FREE voting guide. You print it off, you drive to the voting place and you vote. The cost of voting is literally a few hours every 2 years.
The benefit is you avoid all kinds of moral and non-moral evils. From abortion, to contraception included in insurance, to police state policies, to voting fraud, to forced vaccinations, to welfare $ to illegal immigrants, etc, etc. Sure, if you want to make a moral argument that you don't have to vote, fine. Will you face the consequences of having a bad country and a police state? Yes.
You can make a moral argument that you don't have to exercise or eat healthy too. Will you face the consequences later in life? Yes. I think this type of thing falls under the old saying in moral theology: Just because something can be done (i.e. avoid voting) doesn't mean it should be. The letter of the law kills.