the issue of small business vs amazon exist regardless of the tax policy. Amazon wants it because the places it wants to be are taxing them anyway (Cali, texas, etc) so they figure they might as well get ebay taxed too.
Also, fwiw, this law isn't a new tax. Right now, you're legally obligated to pay sales taxes on the purchases you make in another state but you have to report them. By not, you're breaking the law. This simply forces businesses to do what you were doing all these years (and by doing I mean not doing).