Here are some examples I found from a search of a corpus:
- But in this day and age where everybody is like on Twitter and on Instagram...
- It's a job where you can make a big difference, " McInnis said.
- I even thought there were moments where I thought the cast members didn't really want to be there.
- Kids are at waterfront. They're playing those trust games where you get blindfolded and have to walk around cones.
- So are you from one of those musical families where everybody plays something different?
You will rightly notice that the word where is used in a way that may seem incorrect--none of these refer to places.
In spoken American English, we do this quite a lot, and I most listeners wouldn't even comment.
So why do we do this? Well, in some cases it's simply because using the more prescriptive in which (or something similar) would sound stilted.
There's a bit more to it than this, and I would be happy to expand on the specific situations that we tend to do this in, if you're curious. Just let me know what your questions are.