More competition has not lead to better conditions for workers. We are currently at such a low level of employment that economists don't know what the natural level of employment is anymore and this is still happening to employees.
You're argument that "they would have had it worse" assumes that that Amazon wouldn't have employees these people if they were only making billionaires instead of people worth 100s of billions. How is western society making more money and goods than ever but the average worker is doing worse while the richest are getting richer than ever?
Unfettered capitalism doesn't lead to all boats rising because eventually you run against hard limits like how many ISPs can run wires on telephone polls, or how many tons of freight can be physically moved from point a to point b. Someone will eventually take control of one of these natural monoplies and extract as much rent as possible from both employees and consumers unless they are forced to do otherwise.
To state that, in an era of less regulation than in America's golden age where we see the average citizen's life stagnating or even getting worse, we need even less regulation so that the people who are worth more than entire countries can compete better is at best putting your head in the sand and at worst being actively against your fellow man.
Not everyone deserves a fucking Lamborghini and steak every night with our current technology but they certainly don't deserve to have to choose between food and medicine or to have to piss in a fucking bottle to save their bosses a few dollars in exchange for not being made homeless
Edit:your point about the government in Seattle not helping out because they make more money from people asking for regulations is not something I am arguing against, as you certainly have a point there. I think the main problem is that most humans on an instinctual level would value a 1% gain in their resources infinitely higher than preventing a 50% loss in all of societys resources and so we end up with assholes everywhere trying their best to be the quoted example on Wikipedia about the tragedy of the commons