There's no technical reason for the difference, simply it's up to the merchant & issuer that can arbitrarily set all kinds of limits where certain checks will be required.
It's a tradeoff between convenience and security, different places will make different choices, but generally competitors within a single market (e.g. UK or Finland) will try to make the same choices so they don't get customers asking why they're slower than a competitor.
It's a tradeoff between convenience and security, different places will make different choices, but generally competitors within a single market (e.g. UK or Finland) will try to make the same choices so they don't get customers asking why they're slower than a competitor.