Why do most American police agencies now require applicants to have a college degree?

That's because they mostly are feral people with no boundaries. For example, they'll say you need a college degree now but once you get it then it's all "Oh no, no!  Did we say college degree? What we actually meant to say was you need to be Mother fuggin Teresa and go on a peace-keeping mission in fuggin Afghanistan."

Most major cities in the U.S. now require officers to have at least a certain number of college hours or to have served two years in the U.S. military, which is considered an equivalent.  This is to ensure that officers have acquired enough education/experience to be considered competent in following orders, being able to legibly write reports, and be articulate enough  to converse intelligently with community members.  For your information, there is no such agency as "NYPD highway patrol".  Highway patrol officers are state agents, not local law enforcement.  Also, requirements for being accepted into law enforcement agencies, whether local, county, or state, are certainly not "crap".  In addition to certain academic requirements, a person must pass an extensive psychological assessment and also pass rigorous physical requirements.  To become an officer, one must be considered stable enough to deal with the public.  Sometimes that doesn't work successfully if members of the community are rabid anti-police and they want confrontation. 

Because some statisticians went over a number of police involved shootings and discovered that degreed officers are far less likely to discharge their weapons than are those with just high school diplomas. 

Let's look at the facts here - you are a citizen of Australia.  The NYPD requires that applicants be citizens; you have an extensive mental health history which will disqualify you; my local Police Department does NOT require a college degree.

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When you apply to the NYPD highway patrol you will find that there is no such thing.

VERY FEW, if any require a degree. Many, but not all, require some number of college credits.

As others have stated, the NYPD doesn't HAVE highway patrol.

New account, I see.  How original.  Don't you live in Australia?  

I'm sure there are many answers to your question because every state creates standards and every department can add their own. Many departments did it in my area just to thin out the application because they were getting so many. Another common reason is to allow the person to mature and have life experience. 

"Yesterday?" College has been a requirement of NYPD for over 20 years.