Frankly I think you are just plain wrong. The "strong labor movement" you speak of simply doesn't exist in the parts of any given economic niche where these changes must first take root (because those parts are not trying to wring every cent out of their labor because they don't need to).

For any particular scrap of ground the "labor movement" (in italics because there is no such coordinated movement on the timeline and scale by which these things happen) wants to fight for the fight for that scrap ends at low margin BigCos like amazon who will not give it up until legislated (or until it looks like they might be and they can get brownie points by biting the bullet ahead of time). In unionized industries the BigCos are also the unionized workplaces where change happens at the glacial pace of contract negotiations. Changes come about in higher margin and smaller scale parts of the economy first. If you want Amazon and Walmart workers to have an hour break for lunch (or some other particular policy goal) then you are not going to get that until so long after the workers in the Coors warehouse and the McMaster warehouse have had it that the legislators can feel secure in legislating it.

Here's an example. Say the UAW manages to negotiate with GM that every third Friday should be pajama Friday. Farcical, right? Of course because it's not within the bounds of what we consider reasonable right now. It has to become reasonable first. If you want pajama Friday or any other specific policy goal it has to be within the bounds of what is reasonable. Before the UAW can even broach the subject there needs to be acceptance elsewhere. The UAW isn't gonna ask for pajama Friday at GM unless they think the policy is not crap and they're not gonna think that unless they've done that at the smaller Ford plant and they're not gonna do that until they've piloted it at the tiny Peterbilt factory where they have a better position in negotiations and can afford big reaches. And they're not gonna try it there unless they've seen the policy play out successfully somewhere else first, say the non-union Cat mining shovel plant down the road where they have the fat margins per worker to do that kind of thing. And the Cat plant isn't even gonna entertain the possibility (and the workers won't push for it) unless it's been proven to work in the even higher margin and smaller scale RV industry plant in the next state over.

I'm not going to repeat myself but if you wan workers to have a generous (by our current frame of reference) paid hour lunch break at Amazon's warehouses then the process by which the idea is normalized is basically the same. You can't change policy at BigCo or at the legislative level until you've made that policy = normal and reasonable by doing it other places first. The strength of the "labor movement" is completely and totally tangential to that process and a good argument (though I don't necessarily agree with it) could be made that strong labor institutions (unions) actually hinder the process because they reduce the agility with which decisions can be made by the bigger players.

So if you want pajama Friday at GM or you want a paid hour long lunch break legislated upon Amazon and Walmart, or any other change that looks to be big and unprecedented from our vantage point here today, then you're gonna need to plant the seeds of those changes in workplaces of a completely and totally different setting so that when the change does finally come to the GMs and Amazons of the world it comes at the end of a long bunch of incremental steps because that's the only way change comes to those big places that are deeply invested in and optimized for the status quo.

Costco, Ocean State Job Lot, and other small scraps of the consumer goods retail economy known for treating their workers well and proving you can make money doing so are doing far, far more for the future of workers in Amazon's warehouse than and "labor movement" can do because what those "generous" employers are doing today is what Amazon will be doing in time.