Making tram driving more attractive by paying them more would draw employees away from other industries, who also need people to do the work.

That's how free markets work, though. If there is a labour shortage, places which are important should pay more, to attract people away from other places, who either also raise wages or make do with fewer people or shutter.

This is just inflationary pressure hitting employers, like all of us. Except when it's a person, you just have to tighten the belt, or make do with higher prices, but when it's a company, it's a societal problem where simply paying more cannot be the solution.