Prufrock – sorry, but in as much that such a provision of the SCMA (post #2) would solve your problem, it sounds to me like a Special By-Law that’s been devised only for a specific Strata Plan.
As KWP said (post #3), there is a Model By-Law (17 in the SCMA) that’s main intent is manage what residents have within their Lots such as brightly coloured curtains or balcony umbrellas that can adversely affect the appearance of the building.
That By-Law actually refers to things that are “not in keeping with the rest of the building”, so whilst it may be a bit of a stretch, if the carspaces are part of each Lot (and that’s very likely), then residents storing the things such you describe within them may contravene that definition, because a carpark is for the keeping of cars.
Have a talk with your Executive Committee and Strata Manager about possibly issuing the users of the offending carspaces (i.e. owners and tenants) with a Notice to Comply (NTC) where it can state that it “believes” (i.e. not definitively) they’re in breach of that By-Law and requires them to rectify the breach.
See what happens, and maybe come back after that with the outcome, because the NTC is a mandatory first-step after which your Owners Corporation could pursue the matter further if needs be.