Whatever you want to call it, it's Constitutional, as is the income tax, so you'll need a Constitutional amendment to change it. BTW voting rights aren't the only rights that felons waive either. They pretty much waive the majority of them once convicted.
BTW, just like you aren't forced to, you know, buy things, you also aren't forced to earn income either, and certainly not at a taxable level. Hence, according to your logic, income tax isn't a "poll tax."
This thread delivers on the fail.
Except you're still supposed to file taxes even if you don't earn income, there's a special exception in the law that allows you not to. Basically creating a special "exception" from the poll tax. I already went over that.