We're doomed. My confrontations with sellers at flea markets of purple loosestrife retort is that "it's legal in the state". My response is "But still unethical & hurts America." Getting them to care or think is my useless attempt.

Does not happen so much in the UK. Though in the past we introduced Himalayan Balsam and Japanes Knot Weed, which are still big problems, and now illegal. While the Romans left us Ground Elder which is a perfect pain, and I do occasionally get asked if I stock the quite illegal, though native, Bracken. Do you have problems with these in the States ?

Chinese Wisteria is something I was surprised to find on an invasive species list. I think of that now when I see them for sale at the Home and Garden store.
[ecosystemgardening.com]

Why are the vendors not prosecuted & fined out of the practice?

Some time back I received a notice from my HOA telling me I had a weed growing in my front lawn . Originally from Maryland , I was somewhat confused . In Maryland , crab grass is considered a highly invasive weed , and the only other thing , at least the only green thing in my yard was clover . Clover puts nitrogin into the soil and is planted as a cash crop by farmers . But I had noticed that the crab grass was grown evrywhere as lawns in Texas . I wrote back , although it was brown and ugly , if I removed the crab grass , the soil would wash away , as it seemed to be the only thing holding it in place . She responded that clover was highly invasive and I needed to remove it .