3x 63A is the reasonable maximum a normal consumer would want at their house. Normal houses are around 3x 32A.

Everything over that is a commercial building and they get billed with different rules and measurements due to the equipment they tend to have. Something about three phase engines and power phases in commercial lighting. I zoned out during those meetings :D

Finland has 230V, so if you're from the US with 110V the low current rating might be confusing ;-) I'd also guess that in Finland they also run three phases into each house/unit (we do in Germany), meaning that's 3*63A = 189A. (Or just shy of 400A on a 110V grid). For us that's the default grid connection you get for your house.

As for your guess: That's just a cultural thing I suppose. I've never seen outdoor meters around here.