1) Colorado has had a state use tax since 1937. The rules for that were almost the same even 80 years ago as for the "Amazon tax". The difference is that historically, taxpayers were on the "honor system" to pay the use tax and now, because so many have been DISHONORABLE, Internet companies are required by states to at least report sales to the state, See "Sales and Use Taxes" from colorado.gov. 

2) For those claiming to be polluting less, I doubt you are saving the state a THING. If the product was made in the city where you live, SOMEBODY is delivering it (and if the items are sent even further, the pollution from planes, trains, or semis needs to be ADDED to the pollution NOT being saved).  

3) I'll make a small wager that the folks complaining the loudest also scream the loudest about infrastructure (that they don't want to pay for)?