You probably need to do a lot more typing and include the whole section !
Also, can you calrify, are the properties concerned freehold or leasehold ? It makes a huge difference.
I can only speak for the properties I own, and what's in my paperwork. What I suspect is the situation is that you have bought a house freehold, and with it comes a small parcel of land which is your parking space. So you own the parking space and the house/garden - but you do not own any of the "common areas", ie the driveway/yard. The developer will still own that, but there will be a covenant giving each of the freeholders certain rights - namely to pass and repass over his bit of land to get to/from your parking space.
The except and reserved bit is just keeping the right for any or all of you to run services under the common areas - otherwise it could get difficult in some cases maintaining your services.
Your upkeep responsibilities will extend only to the common areas. The parking spaces themselves will almost certainly be the sole responsibility of the freeholder that owns them. If one of your neighbours wants to put a garage up, then that's up to him provided it does not affect your ability to use your parking space or pass and repass over the common areas.
If you have leaseholds (as is common with flats/apartments) then things are different. As a leaseholder you don't actually own the land or property - you lease it for a long period (999 years is common, though it can be shorter). At the end of the lease, you have nothing - which is why some people who bought properties with (say) only 40 years or less of lease to go will find it gets progressively less valuable as the years tick on.
So <someone> will still own the land and property, but you have a lease which entitles you to use it almost as if you own it.
If you have leaseholds, then your neighbour may or may not own the parking space, and he may or may not be able to build on it.