It's common here too. One neighbor has 2 car garage but converted to living/lounging area (neighbor's wife won't let him smoke indoors), another neighbor 3 car but only 1 vehicle parks inside then a workship and gardening center in more than half. I have a 2-1/2 car garage, but only the 1 newest vehicle gets parked inside. I'd say at least 80% of neighbors, park a vehicle outside so they can use that garage space for something else.
There is a little junk in the corners of my garage, but we have an HOA preventing unattached sheds/barns/etc, so the garage is used for mower/snowblower, other outdoor equipment, gardening/landscaping/crop supplies, a 2nd mini-workshop, automotive tools, general tools, metal shelving for groceries and other misc, deep freezer, bicycles, hoses/extension cords/chains/ladders/car parts/wood/table saw, garbage/recycle bins, lockers, etc, etc. I'd say only about 10% of it is junk to someone who doesn't have the same activities, but then 10% of someone else's stuff would seem like junk to me too.
One thing about having semi-valuable stuff in the garage besides a vehicle is, suppose I drive somewher, vehicle gets snowed/iced/rained on, then when I get home, if parked in the garage I have drain-off. Floor is graded towards a drain, but even then that is a lot of humidity to cause rust and mold, and dirty caked on road grime from the undercarriage when it snows, so prefer to just keep the outdoor elements, outdoors as much as possible. The vehicle parked in the garage only gets driven in good weather, or stays outside to dry if unexpected rain is encountered.
Then again, around here almost all neighbors have a basement. That's where the real junk gets stored.