Is proctored testing necessary? YES.
At least for those who wish to engage in professions like Real Estate, Doctors, Lawyers, Insurance, Specialty Trades (Electric, Plumbing, Etc.), so why not the Home Inspection industry?
What can the public do to ensure that the individual that they hire to do there home inspection is qualified?
Look for someone who has chosen to take the time to prove that they are qualified to inspect your home.
Some examples are:
RBO A Residential Building Official.
RBI A Residential Building Inspector.
ESI An Electrical Safety Inspector.
PE A Professional Engineer.
These designation are available to anyone who choses to go through the required step to achieve these credentials.