@ShionSinX Knowing the cost of living and average income are worth nothing if you don't have a frame of reference, which is what converting it to yen does for these characters. You can tell me all day that someone in Egypt makes 400 pounds an hour and that a loaf of bread costs 31.60 and none of it will mean a damn thing to me because I have no frame of reference to judge it on; for all I know, that's incredibly cheap or incredibly expensive.
Now, if you then tell me that 400 pounds is equal to about 25$ US and that 31.60 pounds is 2$ even, I'll get a much better understanding of what the cost of living there is and if, like with many isekai, you tell me that one copper/iron/bronze coin is worth about 1$ US (or roughly 100 yen) and that the currency operates on a base ten system, I know roughly what things will cost at a glance and whether something is cheap or expensive,
because I have a frame of reference.