Lawmakers complained this created an unfair advantage over local retailers and insisted on regulation that forced Amazon to collect local taxes.
Except that meant that there was no longer any reason why Amazon wouldn't open local fulfillment centers in basically every state, improve delivery speed, lower costs through economies of scale, and make it even harder for the local brick and mortar retailers to compete.
The Cobra Effect[1] is a bitch.
The relevance here is unions are good, and worker rights are good. But Amazon is already working hard on replacing all those workers with robots and automation (who isn't?)
If these workers succeed in unionizing, it will only just accelerate Amazon's quest to replace MOST of these workers with robots.
And then it will be the government's problem to figure out what to do with millions of low skilled workers leaving the labour force at the same time as millions of truck drivers becoming redundant with self-driving cars.
I do not have good faith in the US figuring this out without substantial social upheaval (The rest of the West will handle it much better because of the existing safety net and early experimentation with Universal Basic Income).