Would you apply the same policy to food hygiene inspections? - wait until customers actually got food poisoning before inspecting?
In a railway context - only inspect the track AFTER a train derailed?
The whole point of pro-active inspections like these is to help prevent the incidents happening in the first place.
No, but you need to look at the risks matrix of each and work out what is cost effective.
A train derailing is something likely if maintenance is not kept up, and has a potentially catastrophic outcome. So obviously this is very valid.
Illnesses from poor food hygiene are also very likely (even at home), with less serious outcomes mostly but the likelihood x consequence is enough to justify regular inspections.
COVID though... based on data from last year, there were very few transmission incidents related to pubs. Most people who catch it won't be affected, and now the vulnerable are jabbed. The likelihood x consequence is very low, and I wouldn't - doing a proper risk assesment - see it as a good use of limited resources.
Where would you prefer your hard earned tax money to be put? Improving local healthcare for other conditions, increasing bin collections, helping the disadvantaged people in your neighbourhood, etc (the myriad of other things councils bleat about being underfunded for)? Or spent on COVID marshalls bullying small businesses trying to keep afloat, with the alternative being an incredibly small risk of a moslty mild illness being transmitted? Most people who are symptomatic with it anyway won't feel like going out eating or drinking (especially pointless if you can't taste).
And if you say the fines go into the coffers anyway, then losing businesses who can't trade will mean the treasury net loses out anyway in the long run.