All Bay Area cities have to follow mandatory orders for building quotas from a Bay Area organization called ABAG

No, ABAG has no authority that supersedes any city or planning commission.

  First hand accounts re older properties

... is a crock. Older properties tend to have even smaller building footprint/ total parcel area ratios.

How about one example of any parcel with a residence footprint taking 80% of the parcel area?

As or that Lennar development, you are totally ignoring common area (exclusive and nonexclusive use).