Some rental companies including Payless, L&M, and EZ reserve the right not to rent to you unless you can prove have collision on a car you own back at home, or purchase the company's collision coverage.
Some companies require proof of so much liability insurance on your own car.
If the agent is not desperately trying to make sales quotas and the company is not running short of cars e.g. Daytona Week, the agent might not ask.
View the rental company';s rules, policies, or terms on its website and Travelociy .com and assume the worse of the two applies.
Disney hints:
http://members.aol.com/ajaynejr/disney.htm