Sometimes things are not Black and White.
Yes it is true that only some people CAN ask to see your license it is also true that maintaining good public relations requires a lot of flexibility at times.
The lifeguard may not have the "power" to see your license but can prevent you from using a part of the beach she "identified" too dangerous to be shared by kayakers that day. You may not pay the "price" that day but the kayaker next week will.
The harbor patrol may all of a sudden decide to enforce the rule about not dropping hoop nets in an obscure area of a breakwall because you wanted to make a "POINT" and not show him your license.
If you are legal, and following the rules you should not be too troubled to show someone your license.
If you are not legal, then I and most people want you to get busted!
Hey you never know when the lifeguard you just became friends points you to a nice little honey hole he heard about from another angler.
Just my take on it.
