There is an issue that needs consideration, if you compare to Japan which has enormous cycle usage. Although it is good for air pollution, you end up seeing whole seas of cycles everywhere which is not nice in terms of the aesthetic nvironment. Go to a normal suburban train station and there might be 500+ bikes all in a massive area.
Better than a large car park but we don't get many large station car parks in the UK. At least with mass transit like buses and trains, the vehicle isn't parked anywhere for any length of time whereas most cycles have very low utilisation in terms of hours per day.
It is impossible without registration to know how many bikes are abandoned. Not sure if the authorities in Japan already have a system for dealing with that.
Bicycles locked wherever is possible are not nice to look at but to be fair the seas of parked cars along the streets are also not aesthetically nice and cars move maybe 2 or 3 hours per day, then most of them loot the streets. Abandoned cycle shares bicycles are definitely sad to look at and should be removed as soon as possible especially when they belong to a failed company. Disclaimer: I drive much more than I cycle.
In an area where you store 1 car, you could instead store 20 bicycles (more with better storage infrastructure). If 20% of people switch from driving to biking, you can save 19% of the storage space, which will be reclaimed by the city. The decluttering of the public spaces has a positive aesthetic effect on the urban environment, which is clearly visible in Dutch cities.
In my city there is a team that goes around the bike racks marking tyres with chalk. If they find chalk still on the tyre next time they tie a note to the bike saying you need to move it. If they find the note still there next time they remove the bike.
You should see China. Big sheds crammed with rusting bikes were a commonplace sight, though that was 10 years ago now. You could tell the Americans by their helmets and going 2X faster on fully inflated tires.
Thing is, it doesn't matter. It is a bit of a rubbish problem, but there is no health hazard. If it gets people to ride bikes, that's far better than cars cramming every road everywhere.
They ride pretty slow, and don't lavishly maintain their bikes in general. You see people smoking while riding a bike in the city. This applies to the typical bike on the street. I understand there is a road bike culture in China now but that's a whole other thing.
I didn't get much chance to talk to people on the street in China since I only know a few words of Mandarin. Most of the software developers I was interacting with had better means of getting around. But I did walk past some working class housing, which is where you see these really large bike sheds. I suppose it's a hassle to carry oil and a tire pump down from one's apartment and back up.
Abandoned bikes are a problem here in Denmark as well, but not an insurmountable one. City workers regularly put tags on the wheels of bikes parked at , fx. the train station. If the tags are not disturbed in a month or so, the bikes are removed.
Better than a large car park but we don't get many large station car parks in the UK. At least with mass transit like buses and trains, the vehicle isn't parked anywhere for any length of time whereas most cycles have very low utilisation in terms of hours per day.
It is impossible without registration to know how many bikes are abandoned. Not sure if the authorities in Japan already have a system for dealing with that.