There are types A (Japan), B (US), C (EU), D (India), E (France), F (Germany), G (UK), H (Israel), I (AU) and so on: in which all have a distinct plug shape and differences in prongs. Type A plug is just two straight prongs without a ground while Type B is nearly identical to A but with a ground connection and Type F has no ground attached to the outlet while Type E does, usually this is solved with a adapter (for electronics that are dual voltage and support 50/60Hz frequency).
However, household appliances are typically region locked in the sense of being singular voltage (like electric kettles, toasters, refrigerators, washing machines) since those are intended to not be made for travel (mainly for domestic use supporting only a single plug type) unless you have both an adapter and a transformer. You can’t just plug a 120v 60Hz Toaster (B Plug) onto a 230v 50Hz outlet (Type F socket) with an adapter alone as that’ll blow the fuse.
Most modern electronics (as in laptops, game consoles and smartphones) support dual voltage and frequencies but their default plug type is region locked, so if you’ve bought a PS5 in the UK importing it into the US (the default cable is Type G that comes with the packaging when plugging into a TV) unless you swap cable for a Type B plug but it’ll work fine. Why is there no unilateral plug type that’s “region free” when discussing plug types found in appliances.
There is also a commercial reason. By selling 110v or 220v appliances with different plugs, it used to be difficult or not viable to mass produce stuff on the us to sell over In Europe or vice versa.
Same for pal and NTSC formats. Main reason was producers lock in.
And of course all the other reasons others already mentioned.
The original reason for both plug type and PAL was simply different electrical systems.
Plug type ensure you didn’t plug a 110v appliance into a 220 system, which could be gangerous to the person.
PAL vs NTSC was really just because PAL came after NTSC and attempted to fix some of the color issues in NTSC, but also had to work on a completely different electrical system - and both relied on timing elements within that electrical system.
It wasn’t “lock in”, it started because the two electrical systems were very different (even the prior black-and-white systems were very different for the same reason, 220v at 50hz vs 120v at 60hz). This frequency difference means different timing mechanisms and even alters the number of scan lines.