AFAIK in North America we only have 15A and 20A sockets. Don’t know how the standards are in the rest of the world.

In NA, you can plug an extension cord only capable of 5A and it’s still got the same standard 15A plug and socket on it. And that’s where the common fear comes from: it’s very easy in NA to overload an extension or power strip by simply plugging a 12A appliance like a microwave oven on an extension cord rated for 5A that then plugs in a 15A socket in the wall and there’s nothing to save you there, the extension cord will melt, especially if it’s very long.

The UK doesn’t have such a problem because all their plugs have fuses in them, so a 5A extension would have a 5A fuse in the plug, so you’re safe you can’t overload it, it won’t let you.

The EU and Australia probably have sane standards where it’s not allowed to sell undersized extensions, plus they use 240V so most appliances use half the current which makes it less likely to have undersized wires.

In the end it comes down to the availability of accessories that doesn’t prevent you from overloading them. If the whole chain is capable of the full current all the way to the breaker/fuse it’s safe, even if you have a kilometer worth of extensions the breaker won’t let you pull more.