Stop trying to pass off responsibility. This is that mythical common sense thing. Teach your children, advance yourself, your family, and the human race. Claiming sales tax (which varies based on location of buyer and is 100% out of sellers control) should be sellers responsibility to advertise is asinine.It's not hard to make that work, they have your account if you're able to bid, and your address is part of your account. At the very least, it should say what you just wrote somewhere ... anywhere on the screen when you bid and have a demo tax rate/price included. But no, it's deceptively excluded on purpose as a gotcha.
Your edgy "I'm so good at math" response is just ridiculous. Of course I know math, I can do that calculation instantly; I'm a programmer. For me, it's not just relatively simple multiplication, it's effortless. The fact that places are actively hiding what rules even apply for a given purchase, is a the problem. But lets say someone who doesn't know math, like a teenager wants to buy stuff; why do you need to deceive them?
Instead of trying to convince someone you're anything but a proponent of bad policy and trying to shame people for 'being bad at math" (which isn't even the issue we're talking about), come up with an actual reason that makes sense why it can't be. There really is none though. Europe already has it right; it was hard to explain to my friends when they visited why our system is so stupid. You shouldn't ever visit some place and be deceived by the prices you see around you; that feels third world-esque.
How would you explain it... does it go like.. "Oh yeah.. that's actually -not- the amount you pay. , you have to remember an arbitrary state % tax ... uhhh gee, I forget what it is in this state, then calculate it yourself." Great end user experience there... Imagine the reason for it, being that someone argued that WYSWYG is a bad idea. Good work, friend.
It's not deceptive.
My point on why it doesn't actually make sense was in my post. As well as reiterated in more words above.
North America alone is 10 times the size of Europe, with geographic and other reasons why taxes must be different. This isn't Europe, never will be. Europe doesn't have it right. They have their own rules for a small country sized area. Guess who calculates the tax when someone from Slovakia wants to buy something from me?