Corruption exists in any large institution.
The truth of the matter is you can never get 100% professionalism or compliance. You have to let 'the weed' grow before you can pluck it!
That’s just life, sadly...
There may be a degree of logic in your view BT, but that doesn't mean that you ignore it, pander to it, or participate in it when you are aware of it.
That's rather like seeing a health and safety hazard, so you ignore it or add to it, or in your way, wait for it to become worse before tackling it.
The sooner the problem is 'plucked', the smaller, less destructive and less endemic is the problem. Plus it sets the standard. In addition, the treatment is so less disruptive and so much more effective.
In the instances of the Met behaving as they have done, either it was a climate permeated from the top. Or it was a general approach to work endemic in the oganisation, that surely the top levels must have been aware of and did nothing. (it wouldn't be the first time I've been aware of that kind of behaviour in my experience, although not relevant to prejudice). Or, and I hope that this was the situation, it was a poblem limited to a small group of corrupt officers.
Sadly, there are so many incidents that cause me to suspect that it wasn't the latter. (1. behaviour in this instance, e.g. document shredding, withholding of evidence, collusion. 2 Hillsborough. 3. Jean Charles de Menezies, to mention just three incidents. I'm sure that we can all think of more.)