Could it be trad simply doesn't pay its people well enough to keep them? A hardback cost about $5 in 1960 when I started buying books. That translates to around $50 today. Have salaries gone up 10x to track inflation? And why not if trad wants to preserve its business?
This. This right here. They don't pay them enough. They also know how much they pile on workers. THEY DON'T CARE. Publishers are tech saavy. I worked in trade for years. It's not that they don't know how to use technology, it's just that for decades they fought using it. They were built on a certain model, way before the Internet was even thought of so of course it took them some time to catch on but it has nothing to do with ability. Publishers have BILLIONS of dollars and trust me, whatever they don't know, they bring in tech teams and computer companies like Apple to help them along. I think some forget just how powerful money is. Trade pubs (the big ones) have more access to the most current technologies than indies ever could because we don't have the connections nor the money to be able to. They know about stuff coming out before the public does. For example, trade was dabbling in audiobooks for years before the idea came out the market. They test things for decades to see how if it has a chance of being successful. Same with ebooks. Pubs were doing ebooks before Amazon was invented but no one wanted to read ebooks. They threw a few out into the market back in the early 80s but no one was interested. Back then, everyone wanted print. So by the time Amazon came along (people still didn't want ebooks) but people warmed up to them, etc. Some think Amazon invented ebooks. No way. I believe the first ebook was published in 1971. I don't even know if Bezos was born then. But, just sharing so folks get an idea that this "trade pubs are dumb when it comes to technology" isn't true. There is a difference between being not knowing how to do something and just not wanting to do it. Call it stubborness and a refusal to admit that things are changing. The print model was trade's bread and butter. Why wouldn't they do all they could to preserve it for as long as possible?
They don't pay workers more because they don't have to. Simple as that. Many of these jobs are full of people who don't even have a college education, which makes it harder for them to demand top payment. That's the first thing. Many come straight out of high school and have no experience when they start doing the simplier tasks for pubs. You can move up but mostly pubs aren't paying you big money if you got some job that doesn't demand a top skill. That's like any job. For years, trade has gotten away with paying people pennies, including authors. With all that's going on in the world, inflation, etc., workers can no longer survive in trade with the small amount they make. But this is no different than any company, even Amazon. All companies pay the "little" employees as little as they get away with and they do it because they know that if you leave, they'll find another who needs a job so bad, they will gladly take the amount.
This is why turnover is so high in retail for example. Because most cannot survive off the tiny amount they make and bosses aren't compelled to raise wages when they know someone else who is desperate for a job will gladly come on even if for a few months. So the cycle goes on and on like this. Until all workers can stand up to small wages (and I'm not blaming the workers, I know it's not so easy, but just saying) then it will always be like this. But you will always have folks who work themselves to death for peanuts for whatever reason and that makes it more difficult for workers overall to receive higher pay.