Commercial Photography or Personal Photography

It seems that the security guards at Emancipation Park, Devon House, and Hope Botanical Gardens were not informed accurately.  
They tell the local people that DSLR cameras and high-tech cameras are not allowed on these premises,  
But smart phones, tablets, and small digital cameras are allowed for personal photography.  
And this information is a contradiction of what the signs at these places actually say.  
 
The signs at the entrances of these places say, “No commercial photography is allowed without a pass.”  
But they do not specify the kind of photographic equipment that is not allowed on the premises.  
One should not assume that a person is doing commercial photography because he or she is using a DSLR camera or other high-tech equipment.  
 
How do you determine whether someone is doing commercial photography or personal photography?  
If you do not see someone taking pictures and collecting money, you cannot conclude that the person is doing commercial photography.  
When tourists go to these parks with their DSLR cameras, nobody tells them not to use their cameras.  
 
Any person who is not a professional photographer can own a DSLR camera or a high-tech camera.  
Moreover, some people use these kinds of cameras to take pictures for personal use.  
Somebody should challenge the managements of these places on this important issue.  
The people who visit these places should not have to go through such harassment and disturbance.