States realized they were losing tax dollar revenues through the internet. Once upon a time, only a Texas resident had to pay state sales tax when they bought from Squadron Mail Order. Eventually other states changed their laws that these internet retailers had to collect state sales tax from the state of sale and the state being sold to.
So now, instead of paying state sales tax to one state, you're often being charged sales tax to two different states, your state and the state the business is in.