The complex environment of benefits involves all sorts of perverse incentives, but here's one that is both stark & (up until now seemingly) under-recognised:
for 16-17 year olds living at home, an apprenticeship (which is part of Govt. attempts to get young people into work or training) results in their families losing a chunk of benefits as they become 'independent workers' not children for benefits purposes.... disincentivizing them from training!