Yes, some police officers aren't really interested in guns. Some are only marginally proficient with them. But as Glenn Dee pointed out, that's only a small part of the job.
And on the other hand, I've shot IPSC with some cops, I've been in classes at Gunsite and elsewhere with cops, had LEOs in classes I was helping teach and have practiced along side of some police officers. Those LEOs were interested and proficient; and some of them were training in part so that they could help train others in their agencies.
While some cops are more skillful and knowledgeable than others, denigrating their abilities categorically is inappropriate and uncalled for.
"It is long been a principle of ours that one is no more armed because he has possession of a firearm than he is a musician because he owns a piano. There is no point in having a gun if you are not capable of using it skillfully." -- Jeff Cooper