I found this unreasonable and confusing until one day I read a conservative argument that this is actually a good thing, because it stops the government from increasing sales tax too much. It constantly reminds residents of how much extra they're paying for sales tax and encourages voting for politicians who will reduce sales tax if it's too high. Okay, it's a reasonable argument, I wasn't super against it anymore.
It's fairly shocking to now see this happen, not even as a result of any law but just one of the biggest companies deciding to obey in advance.