It’s not a matter of whether they deserve more money or not, but about forcing the management to up the pay. The company wants to pay the least and pocket the most, the worker wants to earn the most and work the least. Each side wants what’s best for itself. As for the promotion ladder, this industry is rather limited and so is the compensation in higher ranks too. Some people are really not very bright, but are at least prepared to get off their arses and do this kind of boring, tiring, repetitive work every day. If they feel they are getting fucked and can squeeze the company for more cash, without being laid off or forcing bankruptcy, why not? It’s not like the bosses running the show give a fuck about them.