Shouldn't we welcome a decline in prosecutions?

This rather puzzles us:

The number of drivers fined for using mobile phones has fallen to a record low, amid fears there are not enough police patrols to catch offenders.

Some 38,600 fixed penalty notices were issued by police to offenders in 2018 compared with 53,000 during the previous 12 months, according to Home Office data.

This is the lowest amount since current records began in 2011.

Fewer people being fined could be because the same level of offences is happening yet fewer are being caught at it. Or, of course, it could be that the incidence of the offence is lower:

AA President Edmund King suggested more offenders would be deterred from using their phones and caught if there were more police patrols.

Well, yes, but we still need to know whether the decline is because of not catching or not doing.

The Home Office data also shows that the number of fines issued for not wearing a seat belt rose by 17 per cent last year, while there was a 5 per cent increase in speeding tickets.

Careless driving fines excluding mobile use were up 20 per cent.

We seem to be catching other people committing other offences in greater numbers. It seems unlikely that it’s a lack of catching going on therefore.

Fines for using mobile phones at wheel at record low amid concerns there are not enough police to catch drivers

If the incidence of the offence is falling then what’s the complaint again?