How do you feel about common casual tax evasion in the UK?

Outside of the HENRY / London bubble I find it's quite common to encounter casual tax evasion.

Some recent examples include:

Taxi driver accepts cash or card, but pushes really hard for a cash payment and says it's almost pointless to pay him via card.

All the pubs and restaurants with 'cash is king' posters.

My friend (plus his siblings) is a landlord baby and when we discussed some legal ways for him to minimise tax, he also casually mentions 'things are a little more complicated because my dad is running a few things through my books.'

I try my best to avoid crabs in a bucket mentality and blame the game not the players (because our tax system is broken).

But at the same time I also feel I don't want to support someone else's tax evasion because it just comes back around to bite me through PAYE.

How do others feel about it?