Back in 1991 when i started to study photography as a student, image making was still largely a film based affair with no visible sign of the digital revolution on the horizon but probably the biggest change I've seen has been in the perception and attitiudes towards photographs and photographers.
In 1998 a case was concluded against a street photographer on the premise "that it is illegal to publish a photograph of someone without written consent". Fortunately the case was thrown out but the issue is still open for debate. My own opinion is that the photographed person should have some say only if the image is used in a way that discredits or harms their reputation. The definition of that can be argued by the lawyers but if a photographer cannot work freely in a public area like a street, we end up with no documentation of society and the way we life now. In the past, local photographers would photograph their community at work and play and would become important chroniclers of history. These days to be photographed is often portrayed as bordering on an invasion of someone's human rights ( which it is, if it is harrassment) and yet photographing the everyday event is important.
A photograph taken of a present day street scene will attract very little attention but revisit that image 30 years later and the street, vehicles, clothing and many other things contained within that picture take on a entirely new meaning. Some of my first images taken in London in 1985 have already started to take on new meaning as historical records of the time and yet they were only taken as a record of a visit to see my auntie and uncle.
That's just the beauty of photography !