That's the way the laws are written. They put the onus on the consumer. The consumers are to blame for not reporting and paying the tax. It's been that way forever, because no one could justify trying to force an out-of-state company to track the hundreds, if not thousands, of state/local sales tax laws when it had no presence in that state. With the advent of computer systems and databases, these things could be done, but it would still be a nightmare for most companies.
For example, in New Mexico, we have a gross receipts tax. It is similar to, but not exactly the same as, a sales tax. It's more like a Value Added Tax (VAT). Each and every local jurisdiction and county has the ability to set a rate over and above the existing 5.125% state rate. These rates often change quarterly. There are 136 municipalities and 33 counties. Some municipalities (Rio Rancho) for example, are split between two counties. This means that, depending on a street address in Rio Rancho, the tax rate could be either 8% or 7.4375%.
Right now, Amazon has agreed to collect the base state rate from all sales in New Mexico, but to track it at the proper rate for each municipality would nightmarish, even for them.
That is simply not true
When I go to a local retailer, I cannot tell him to not charge me the tax, and I'll pay it myself.
This really puts local retailers at a 7-10% price disadvantage to the folks like Amazon