Assumes that there is a single maximum slots a player can have instead of setting this value per garage. Maybe a player should only be able to store 1 vehicle in a public garage, but 3 vehicles in a house garage. This is not possible with the current design.
Assumes that the limit should not change based on the player. Maybe a house garage for example would be unlimited for the owner only, whereas guests can park a max of 1 vehicle. In the current design this is not possible as limits are enforced for all players, or none.
Assumes that the limit should be player based rather than garage based. While a player based limit makes sense for interacting with public garages, player owned garages, such as job and house garages, may make more sense to have a garage side limit. This could still be implemented in the future however as a separate feature.
Limitations of this design