People may take it for granted that their 'phones work everywhere but it was not ever thus. I used to have to borrow a tri-band 'phone for visits to the US. My normal mobile worked everywhere except the US. Later on I had the same problem with South Korea.
There was a time (back in the analogue TV days) when a TV bought in one European country wouldn't work in many of the others. Digital TV is based on common underlying compression standards. (Although, even here there is scope for creating artificial incompatibilities.) Unfortunately there is no common transmission standard, although DVB satellite transmission schemes are fairly widely adopted.
People can now move almost anywhere in the world reasonably cheaply. Some of their gadgets are useless outside their home country.
Many of these problems are caused by "special interest groups", manufacturer inspired protectionism and plain political stupidity.