The issue is that these sorts of fields are notorious for not liking to hire more than they have to. They'd rather overwork their existing staff than hire more.

I knew a guy who worked as a machinist, and basically everybody in his company worked 60+ hours every week all year, and the company compensated proper overtime the entire time. The company basically paid double wages for 50% extra labour, and that's presuming that the employees even did 50% extra work for being tired all the time. The guy quit the job because he couldn't take it after a few years, so in the end the company had to hire more help anyways.

It's an issue of culture as well as many other things, and few people want to go against tradition.