Late answer, but this is rather common to a lot of European languages. The standard is typically using spaces for digit grouping, and a comma (instead of a full stop) for the decimal point, though there are odd exceptions in some places (I know there are some locales that use spaces for grouping but a full stop for the decimal point).
I had to look up what the long short scales were; I had never heard of them before now. For anyone else curious: https://en.wikipedia.org/wiki/Long_and_short_scales
It's not a universal truism of mathematics - that's the whole problem. It's regional. In other regions, the words are defined such that a million million IS a billion. It is not a question of mathematics, but one of linguistics. What is "mathematically correct" is that 1 000 000 x 1 000 000 = 1 000 000 000 000, but exactly what you CALL that number varies - not just between language families (Swedish isn't the only one to use the long scale, I'm pretty sure), but even between English-speaking regions.
SI prefixes, on the other hand, ARE standard. 1 Mm = 10^6 m, and that's true wherever you are. This linguistic collision of terms is why scientific notation exists
I am a native UK english speaker and I have no problem with saying some one has a million friends. Probably a bit of an exaggeration though but not uncommon in spoken english. We would never say she has million friends or hundred friends. We would always put a number or just an "a" before it.