Final answer:
It is illegal to park in handicapped parking spaces without the appropriate placards or license plates. The Americans with Disabilities Act (ADA) of 1990 enforced this regulation to ensure accessibility for those with disabilities. Violations can lead to fines and are related to the concept of 'effective demand' in economics.
Step-by-step explanation:
The question addresses legal regulations concerning parking privileges for individuals with disabilities. Specifically, it is indeed illegal for persons without the appropriate handicapped or disability placards or license plates to park in the handicapped parking spaces.
This is enforced under several laws, including the Americans with Disabilities Act (ADA) of 1990, which ensures public accommodations are accessible to those with disabilities. The ADA, along with state and local regulations, typically require that designated handicapped parking spots are reserved for those with a valid handicapped placard or license plate. Violation of these parking regulations can lead to fines or other penalties.
The concept of "effective demand" in economics indicates that for a demand to be considered effective, one must have the willingness and ability to pay for a good or service. In this context, even if a person desires to park in a handicapped space, without the proper authorization (a placard or license plate), they do not have the 'effective demand' or legal right to occupy that space.