Most photographers seem to have their own take on what street photography really is, whether it's urban photography, whether it always includes people, what differentiates it from travel or documentary photography, whether it has to be candid.
I like the current Wikipedia definition:
Perhaps more than any other genre it is difficult to define the boundaries of street photography, and most street photographers don't necessarily care how their images are classified. There are overlaps with documentary photography especially, but also portraiture. Street photography is often candid, in that the photographer has no interaction with the scene being photographed. But sometimes the photographer does initiate an interaction, intentionally or otherwise. Perhaps someone reacts to the presence of the photographer. The initial reaction could still be deemed candid, but the longer the delay the more likely that the subject or subjects will start to pose in some way. Taking that further is the street portrait where the photographer intentionally approaches a stranger to interact and offer to take their portrait.
There is certainly overlap between documentary photography, photojournalism and street photography. The intentions may be very different. A documentary is usually aimed at a specific project, and in-depth study over time to create of body of work centered around a particular topic or issue. Photojournalism is often focused on a specific event, with the aim to report what happened through text and images.
A street photographer is usually more spontaneous in terms of the subject matter and the types of images produced. They may have no specific goals beyond recording life on the street as they see it, with as much or as little bias as they choose. There is also the aim or desire to produce an artistic image, whether that it through aesthetic beauty, careful composition or a striking juxtaposition.
But a street photograph often documents, and a documentary project or photojournalism assignment may well show beauty and artistic skill in a street environment.
One complaint I've heard numerous times is that street photography is often just lazy shots of someone walking past a wall. It's a fair point, and I've taken a few of those images too, but isn't it the case in every genre that there will be some relatively easy images? And some that are just plain bad. Not every street photograph is going to be a nuanced masterpiece, and there's always a learning process and experimentation. There will always be some simple shots, probably making up the majority that are shared online, and others that take more skill, patience, effort, courage or commitment to achieve. We might aim for the latter but hopefully not loose the spontaneity that can make street photography so enjoyable.