More importantly, why does the hardness of doing a thing give you special status to make claims without proof?
It doesn't. But, "God doesn't exist" is not a claim, it is a counter-claim to the claim "God exists". The very concept of a higher power didn't even exist until people started claiming without evidence that it did exist, and it's been many branching games of telephone of that original unproven claim since then that has resulted in basically every major religion.
The counter-claim of "God doesn't exist" needs no proof beause it is countering a claim that also has no proof. If and when the original multiple millenium old claim of "God exists" actually has some proof to back it up, then the counter-claim would need to either have actual proof as well to support it, or debunk the "evidence" if possible. But again, the original claim is literally thousands of years old and still has absolute bupkis to prove it, so... I'm not too worried.
ETA:
The universe is massive. There are teapots here. Why is it not plausible to believe some other alien race would not also construct some kind of teapot? Also, consider the fact that all teapots here on earth are literally teapots in "outerspace" in some sense.
The other person you replied to worded this bit poorly. The original analogy is trying to convince people on Earth to believe that there is a teapot(which is too small to see with a telescope) orbiting the Sun independently somewhere in between Earth's and Mars' orbits. It's completely illogical to believe seeing as humans haven't sent anything without scientific value beyond maybe the moon, and there's no evidence aliens have visited our solar system let alone left a teapot in orbit. But since it can't be proven there isn't a teapot orbiting by itself, does that mean you should believe there is? No, of course not.
This ties into the part you absolutely agreed with. The word "God" as it is defined now would not exist without the original unproven claims that God. Even if you're not responding "God doesn't exist" directly to someone who said "God exists", you are if nothing else still responding to the original millennia old claim that they do exist. For that reason, it is always a counter-claim.
As for what makes counter-claims different from regular claims, it's simply that the burden of proof lies first with the original claim. A counter-claim has no responsibility to prove their claim until such time as the original claim presents evidence supporting itself.
I absolutely agree. That was kinda my point. If the claim ever did get some actually noteworthy evidence, then it would certainly need to be properly proven or disproven... but I don't think that will ever happen.
The problem with that is I at least in theory could have looked up the tax code, remembered it, and then told you it correctly. Sure, I could have lied or remembered wrong, but it was 100% within my capacity to give you the accurate information, and even show you where I got the information from. With a claim about God's existence, that's impossible for either side of the debate as far as we know, and since the original claim was "God exists", that side is, possibly forever, stuck holding the burden of proof.