For example, in the UK, the police have the legal power to search you if the have reasonable grounds to suspect that you have something on you in a few categories, like drugs. There are even (yet more controversial) powers to search people just because they’re in a specific area (though there are restrictions on why an area can be so designated). You don’t need to be arrested or handcuffed for this, although you might be.
Let’s not make such sweeping generalisations.
For example, in the UK, the police have the legal power to search you if the have reasonable grounds to suspect that you have something on you in a few categories, like drugs. There are even (yet more controversial) powers to search people just because they’re in a specific area (though there are restrictions on why an area can be so designated). You don’t need to be arrested or handcuffed for this, although you might be.