>Lots of office jobs have been badly paid compared to skilled work
"Pay" is not a scalar measure, it is a vector with multiple components. Roughly speaking, pay is short for "pay to quality of life at work ratio". Which incorporates everything a person thinks about when choosing what to sell, including volatility of pay, what coworkers will be like, possibility of injury, commute time, the weather and conditions you will be working in, potential upward movement, potential for harassment at work, location of work, potential of finding a spouse with xyz characteristics, etc.
Swinging hammers or plumbing or whatever can strictly pay more, but not may not be sufficient to incentivize people to choose to do them over being paid less in an office. Pay someone 300,000 GBP per year to do 40 hours per week of plumbing working, and the UK would have plenty of plumbers, and parents would be recommending their kids to become plumbers. But if the differential is only 10,000 GBP? Maybe not worth it.