Safety was one significant concern. 230-240V is more likely to stop a person's heart. 220 is available in most US homes for specific cases where it is more practical.
Speaking from experience, I don't think it is uncommon for a person to have been electrically shocked at some point in their lives --- often when they were a child.
Maybe common in the US. Europe takes plug and outlet design more serious (as a consequence of 230V), and while the UK plug and continental Europe's Schuko plug are very different both make it basically impossible to accidentally shock yourself.
Not impossible with the Schuko, it's still possible for something to get caught in it and touch the pins when it's partially inserted, that's happened to me. It's better when only the tip of the pins are exposed, as on the UK plug and the Europlug.
On UK plugs at least, there are shutters and you need to insert something into the earth pin slot before they will allow you to access the live/neutral pins. On better sockets, the shutters then need simultaneous pressure on both live/neutral to completely release. The actual contacts in the socket are recessed too.
UK plugs and sockets are really, really, really safe. Except to stand on.
There is a hole cover plate that has to be pushed by rounded plug pins to pivot and unlock the socket holes.
You can try pushing with something like a screwdriver (to test for live) and it's hard to pivot the plate (feels like it needs both pins to pivot), and a non round tool snags on the plastic cover plate.
In the US code requires shutters so you can't stick anything into the socket other than the correct plug (IIRC as of 2008?). Other responses are implying the UK (and I assume EU) now require that too.
On the other end, in India I saw a power strip that would accept EU, UK, or US plugs. I took one look and refused to get close, but someone else plugged my laptop in and it worked. (everything got 240 volts, which my laptop power supply was fine with)
No EU-regulation for that I think, it depends on the country. British Standard 1363 has had mandatory safety shutters since it was introduced in 1947 (not sure if you could still use the older British Standard 546). Here in Sweden there is a building regulation from 1988 stating outlets should be placed or designed to make it hard for children to insert things into them. I was surprised to learn that wasn't common in the US, at least until recently.
Wire insulation deteriorates over time. Rodents like to chew through it. Water can find it's way in through plumbing or roof leaks. Higher voltage is more likely to start a fire in these instances.
I'm in Europe and I've been shocked a few times by 220V and I know plenty of other who has too. It's usually not from regular wall sockets, but wires with broken insulation or working on things where parts of a circuit is uninsulated.
Safety was one significant concern. 230-240V is more likely to stop a person's heart. 220 is available in most US homes for specific cases where it is more practical.
Speaking from experience, I don't think it is uncommon for a person to have been electrically shocked at some point in their lives --- often when they were a child.