Why are many Nigerian (Lagos) buildings, homes in particular, constructed with very inadequate parking space? I try not to see such as nuisances but then I wonder what goes through the minds of landlords, architects, civil engineers, town planers, graduates of estate management, and the likes.

Many building Proffessionals are equally disturbed so Your tittle may not be very appropriate
Most buildings with 6 flats of 3 bedroom each, on 3 floors, occupying just a standard plot of 60' x 120', at least in Lagos today. were originally designed with the whole ground floor as parking space, and just 4 flats above.

The conclusive contraption is often the result of conivance between Landlords & less qualified Govt agents, & building artisans & contractors

Also times have changed & there is need for an overhaul of our Town Planning Laws & building codes. This will include criminal penalties for professionals, particularly on the Govt side. Economically years ago one would not have expected occupiers of tenement buildings popularly referred to as 'face to face' to own as many vehicles as they own per building of say 8 rooms today, where 6 of them may be car owners in cties like Lagos

However bringing this to public attention as you have done is important, collectively we all can be the change we seek.

The Land is Green