So the "someone opening a door" bit is the first argument I hear as every time against lane splitting, Frankly in 53 years riding in California and probably 10s of thousands of actual lane splitting miles in that time, I've never seen it happen. None of my riding friends here have ever had it happen to them either. As most lane splitting is done on the freeways, there are no pedestrian crossings there.
Here is an example of my typical commute before I transitioned to home based work. No doors, no pedestrians, complete with accident scene at the end.
https://youtu.be/EBc2ChJ3kas
This was on my previous ST1300.