Comment by klodolph

The actual risk is that a cheap charger fails in an unsafe way, and exposes users to unsafe voltages. You need, internally, the right creepage and clearance distances, and you need to use the correct parts in certain places with the correct failure modes (e.g. must fail open or must fail closed). Some cheap chargers are not built to the same safety standards. You won’t notice anything unless they fail in an unsafe way. Unlikely, but possible.