I don't think frivolity is necessarily binary — it's more of a spectrum. On one end of the spectrum you have tunnels that connect landmasses separated by massive bodies of water, and allow emergency services to operate efficiently (where the only alternative is a giant suspension bridge).
On the other end of the spectrum you have tunnels such as the LVCC Loop which help convention goers and tourists avoid what is effectively a brisk walk or bike ride (this is also largely a glorified Tesla marketing campaign).
> just like many other construction companies
I'm not sure I believe disfiguring blue collar construction workers is just standard business practice while building a small tunnel just because you posted a link stating that construction can be dangerous. Of course construction as an industry is going to be more dangerous than childcare for instance (and therefore over-represented as an industry in statistics), but that doesn't mean you waive off every accident and chalk it up to a business expense.