It wasn't actually South Dakota's fault per se. The supreme court had made it known that they were willing to reverse the prior decision if the right case was brought before them. Of all the pending cases in the county, the South Dakota case was felt to meet all the requirements so that was the one that was rushed to the supreme court. My understanding there is a "group" of states that have agreed to all the same rules where others have there on set of rules. For example, Texas will only require sales taxes to be collected if your sales are over $500k in the state over the previous 12 months. Sounds easy, but that is a rolling 12 months. So you could in theory have to collect in some months and not in other months depending on your monthly sales figures. Texas is also considering a set sales tax percentage instead of having to figure a state tax and local taxes.
Texas is requiring collection to start October 1, 2019. California started theirs April 2, 2019. A lot of states started Jan 1, 2019. I believe all states agreed they would not go retroactive for collection.
I also don't get the Trump picture.