low efficiency in mobile phone charger
Your assumption that the adapter actually draws 0.2 A from the mains is simply WRONG. What is listed is the maximum current.

This is the current that will flow for a very short time when you plug the adapter into the mains while mains is at the peak of the sinewave (maximum voltage) and the adapter's smoothing capacitor is completely discharged. Only then 0.2 A will flow for a fraction of a second.

If the adapter was really that inefficient it would get very hot and I mean so hot that you will not be able to touch it.

Typically these power adapters have an efficiency of around 80% to 90% and not the 10% to 20 % you claim. Your assumption and efficiency calculation is simply wrong.

but then same peak should be mapped to the output No it is not, it simply does not work like that. The 0.2 A is a peak value, after initial charge of the smoothing capacitor the mains current will be much lower.