Unfortunately this isn't the sort of thing where you're going to have an obvious answer because the causation chain is really long.
1) Person sits in traffic getting to work
2) Person notices Bird scooters zipping by them
3) Person ALSO notices that their company has to pay them the cost of their parking space if they don't use it (in California at least - see parking cashout law)
4) Person starts taking Bird, and enjoying the cash from their company
5) Person's office now has an extra parking space
6) Person tells coworkers about how great it is getting to work 20 minutes faster and making a couple extra grand a year
....
(wait a year or two)
7) 20 of person's coworkers are now doing the same
8) Office building has more open parking spaces
9) Business leasing office space says "I actually don't care if my office has loads of parking, most of our employees take scooters/walk/transit/whatever"
10) Office building developer says "wow we can make more money if we build the office with more units instead of more parking"
11) Office building development petitions city to reduce legal minimum requirement of parking spaces
12) (couple years later) FINALLY gets the parking minimum reduced after overcoming the screams of NIMBYs who think only a few weirdos are the ones riding scooters "because the scooter/bike lanes are empty". (Related - this is a problem with people thinking bike lanes are unused - turns out a bike lane with 500 bikes an hour will LOOK emptier than a road with 500 cars an hour because, well, bikes are faster (in congestion) and smaller)
13) More of that space can be used for offices, homes, or just not built on, etc.
So if we can design an experiment that can track all of that, awesome, but in the meantime it's messy.
If nothing else, just making parking compete like any other land use reveals that there are people who would happily repurpose the land for other things. You can park your car in the absolute most prime land in downtown Santa Monica for $525 a month. That is CRAZY. I would pay ~$1600 a month for a few of those spots and build a studio in an INSTANT because you could rent that out to a human for about $5,000 a month.
But instead we use taxpayer money to subsidize sleeping spaces for cars, even though there are humans who would happily pay to sleep there instead. It must really suck for the person who can barely afford their $3400 rent at 16th and Santa Monica blvd that their taxes are helping provide affordable housing for cars right on the beach.