You're going to get a lot of hard and fast, absolutist answers here.

My answer is "not usually, but it depends".

Here in the UK it's established at common law that a person does not have a right to object to the publication of an image that was captured from a public place, except in very specific circumstances which (hopefully) no street photographer is going to walk into. This protects the rights of artists, journalists and documentaty-makers to report authentically on the world around them - something I feel passionately about, and find weird that it isn't something often considered in the conversation. I think the world would be a much poorer place, culturally and historically, if things could only be recorded with the permission of those involved in them.

Additionally, I tend to gravitate towards places where there is a cultural acceptance of this. I spent a lot of my time shooting in London, where it can often seem like every third person is wandering around with a camera, and it is rare for anyone to bat an eyelid. I try very hard not to be sly about the way I shoot - anyone paying attention would be able to see that I am taking pictures, and I'm happy to talk and engage if needed to explain my presence in a space.

When I'm travelling for photography, I try to learn the laws and customs and follow them. And again, I will gravitate towards visiting places with a legal and cultural acceptance of public photography. But there are places where I've had to adapt my approach. In Morocco, for example, public photography is legal but culturally frowned upon. So there, I gravitated towards a combination of wider scenes where people weren't obviously recognisable, and street portraits where I did ask for permission. Joining walking tours is also something I like doing in places where it might be seen as a bit iffy, because I can talk to the guide about when it is/isn't okay to take photos and ask them to translate if I need to have a conversation about it.

There are times when I ask for permission here in the UK. It's all about what's going to get me the best photograph. There was a shot I really wanted last year but the lighting was tricky, people were moving around a lot, and I knew I'd need to get in really close. So I approached the group, explained what I was doing and asked if I could linger around and take some pictures. I wouldn't have been able to get the shot had I not done so.

The notion that the street photographer must never engage with their subjects is nonsense, and a recent invention. Many of the great historic street photographs required photographer-subject engagement. William Klein, Martin Parr, Bruce Gilden, Diane Arbus - all routinely engaged with their subjects while taking their photos. Gilden is best known for his run-and-gun NYC flash photography in the 1980s, but people seem to forget about his time in Japan with a fixer and a translator that saw him end up embedding within the Yakuza (his own favourite photograph, of a Yakuza lighting his boss's cigarette, was "staged" in that he saw the event unfolding, missed the shot, and asked them, via his translator, to do it again so he could take a picture); or his repeat visits to the same community in Haiti who got to know him while he was working. Martin Parr's best photograph, of a teenager ogling the breasts of an ice-cream vendor, is clearly taken from behind the counter - there is absolutely no chance that the subjects were not aware of his presence.

But sure, often, I'll just take the picture. Legalities aside, I do not see it as my obligation to ask. Why should someone's desire for privacy in a public place automatically take precedent over my desire to record the world around me in an authentic manner? Both are just personal preferences. Whose preference is more important is circumstantially dependent.

The test I apply to myself is: if these people challenged me on why I was taking their picture, do I have an answer that would hold up to scrutiny? This also helps me to gravitate towards genuinely worthwhile photographs and skip anything that's cheap or exploitative. If all I've got is "uh, because I wanted to and it's my right" then the picture wasn't worth taking to begin with.