this is because browsers have very sophisticated algorithms to detect the encoding because this was such a frequent issue. (and yes, UTF-8 adoption/support has been growing, which also helps)

being German and working in a multi-national company, i can confirm it is still very much an issue with software that doesn't handle this. Excel is one of the worst offenders, document corruption is rife especially when going between Excel on Windows and Excel for Mac. this is because Excel doesn't to UTF-8 as default for legacy reasons (I think), but also either doesn't have encoding detection or has very bad encoding detection.

As am I. The encoding detection used for a standardized(!) feed file format I had to write had cyclomatic complexity of 16 and only supported 4 encodings(X). On the other hand it was almost always correct. How you would do that on a global scale is beyond me.

(X) I hear you ask, 'Why would you do that even!?' Try telling tiny companies without IT department what an encoding is. It's faster to just figure it out on the receiving side.