To be fair. Involuntary bumping is happening very rarely. Airlines don't have an interest to bump passengers. At least in Europe this can be relatively costly

To be fair. Involuntary bumping is happening very rarely. Airlines don't have an interest to bump passengers. At least in Europe this can be relatively costly as in up to 600EUR compensation per passenger. Add hotel rooms, multiple restaurant visits, taxis and communication costs to that. Add the image loss if this happens too frequently. Airlines employ extremely complex math and statistical models to avoid bumping passengers, while filling the plane to capacity and mostly it works out. If it doesn't they usually find volounteers, who are willing to be bumped, provided that they are fairly compensated and provided with a reasonable alternative.