When applying for service with a police agency one has to expect that if your application is accepted and you complete training that you are walking into that thin blue area between allowed and not allowed. During training we are told every manner of horror story and incidents that would cause the blood to run cold in one's veins. I policed in a Canadian City from 1976-2012 the changes in society I saw were astounding, just the changes in telecommunications and innovations of computers and other hi tech wizardry is mind boggling. We as humans are violent by nature and sometimes by nurture, it is obvious this mom has been providing her son with all the skills and mind set to allow him the become a major league thug. Police are a necessary evil, why evil? because it is not an activity that one can do for very long without becoming a far different person than the wide eyed kid who first aspired to serve. The very humans we depend on to be our peacekeepers must be more violent, more prepared and more willing to cause harm to others on a daily basis as if you are working an eternal war zone. So yes police expect to attend a pool party out of control but the pool party hi jinks of the 1970's are not the same as today because the children of today have that gamer, instant satisfaction mind set that makes them feel entitled, empowered and justified in combatting the police. There will be changes in policing and how police are hired and set limits of service, because police will ever be seen as the medium that must be changed as opposed to being supported they are constantly under review, which is not a bad thing but eventually you are going to run out of people who want to serve.
You bring up two very important points. Many modern police departments are already ahead of the curve on training and code of conduct compliance for officers. Unfortunately those changes are only being made where they can be afforded. Many jurisdictions can't afford the same levels of modernization of equipment, personnel evaluation and training and pay as others and hiring is often done though word of mouth recommendations in smaller departments.
I don't think that the problem was systemic in the case of the pool incident. There were several officers present but only one blew a fuse. I'm no psychiatrist but just watching him in action for a few minutes screams the fact that he, this individual who was caught on camera verbally and physically abusing minors is not suited to wear a badge and a gun. Ideally I would like to have seen another officer intervene until such time as his emotions were placed in check and he could regain his professional demeanor.
Another poster recommended requirements like 4 year university degrees and psychological and physical stress analysis as well as higher pay and the department in my town has just those requirements and training is ongoing and covers procedural legality, cultural sensitivity and awareness (Spanish isn't required but it is promoted and training is offered for free) and physical and psychological screening is ongoing. The problem is that these officers are often heavily recruited by other state, county, local and federal law enforcement agencies in the Washington, D.C. area offering higher pay, better benefits, greater promotion potential and status. Governance is no less a business than any other and higher standards for policing and other services are cost dependent to a degree and over the past half dozen years, a great many U.S. law enforcement jurisdictions have plunged into negative budget balances and as a result have cut back on services, sometimes drastically and that not only affects the size and readiness of their police departments, schools, libraries and other public services but also tends to heighten the tensions of Walmart shoppers. Tough times place people in tough decisions and increases their chances of choosing wrong.
Surely Walmart stores hire security personnel and I know they've got cameras covering the entire stores. In my view the store management's failure to identify and neutralize the problem between two of its customers is the real problem in the instance shown, not the police, not 'society' and certainly not that unfortunate little boy with a wild hog for a Mother.