Presumably because it's cheaper. Ours was also originally in home; the utility recently came through and replaced all of ours with exterior units, likely at great cost (horizontal drilling machines aren't cheap)

I suspect the tragedy in Pennsylvania [1] was the catalyst. There are lots of potential issues with keeping these things indoors.

1. https://en.wikipedia.org/wiki/Merrimack_Valley_gas_explosion...

For what's worth my father's old apartment somewhere in central europe has this inside of the apartment as well, common in older buildings, my 60s built Prague residential building already have them in basement, we have also (central) heating meters outside the apartment measuring the supplied hot water, same with electricity/power meters (with online readings over fiber).

Only thing inside my apartment (well technically it's vertical shaft going through whole building, but there is small access door to meter in every apartment in case you wanna stop the water in the apartment) is remotely read cold/hot water meters with antenna.

They are usually checked only once a year anyway.

Meter still looks very accessible to me