This can be changed from country to country due to PANs amendments, but at least in the countries I flew mayday is used in immediate emergency that requires immediate landing (immediate means right now, wherever you are)
An inexperienced person at the controls could very easily lead to an immediate landing.
But really, when all is said and done, I think everyone would forgive inexperienced people for not respecting differences between countries when it comes to correctly using MAYDAY and PANPAN.
