James posted somewhere once, possibly on ukvac, when i was asking about the difficulty levels on something at AC, that he likes to set them on the easiest setting because he always used to dislike how arcade operators back in the day liked to do the opposite and set everything on hardest to maximise revenue.
mr do, dig dug and frogger are definitely on the easiest level. I mentioned to you recently I thought that 1942 seemed easier than mine which is at at TG settings..... dig dug has a crazy volume of extra lives, but i quite like that to be honest.
i woudnt be surprised if the majority of games at AC are just set at the difficulty level they get them at, and they dont make a concious effort to alter them, unless someone requests it.