It depends on the local norms. Where I live, 1,004 is decimal, 1 004 or 1'004 is 1004 which makes it even more clear than the en-US default. That is, the 1.004 variant is never used, and if it is, it is assumed to be a decimal (misspelling) of 1,004.
Ah makes sense. In Canada we were taught to use spaces to separate, and decimals for decimals. But being stuck so close to the US we end up with a mess of everything.
In Denmark for example the decimal and comma are reversed in meaning, so you would not have a Danish 100,000,004 because that is an obvious non-Danish number.
