I thought you left but you're back now? Personally I think that was just a rouse to get more responses. So here is mine.
I agree with you that UP Police needs to fix its apearance. Not all but a few. I personally think BNSF Police looks more professional and it fixed the image BN Police had before the merger. However if you have such a personal problem with it yourself then I feel you should contact the agency in Omaha in a professional letter.
You should do more research on railroad police and law enforcement in general. I am a deputy sheriff who wants to eventually become a railroad police officer. You need to realize that railroad police officers are controlled and regulated under the state they are commissioned in. There are rules and laws regarding railroad police just like any other peace officer. You also need to realize that as a police officer of any kind if you let someone run over you then you are going to get killed. There are people out there who will kill you if you let them have that opportunity. When I make a contact I am in charge whether I am "in the right" or not. If you can't control your contact you will make it nowhere in the law enforcement profession. If you had a negative contact with law enforcement you should think about what made it that way and why you were in that situation to begin with. Then decide what if any professional steps should be taken to remedy it not cry to a bunch of people you've never met nor seen on the internet who can't and will not do anything to fix the (if any) problem or make you feel better.

Railroads are not the only companies in america that have their own private police department. There are many private police departments out there. That is regulated state to state. Research it on the internet. Perhaps, there are some even in California? Why do railroads have their own police departments at their own expense still? Because no one else wants to deal with it. That's the bottom line, period. Would you rather have (and pay for) a government dedicated team of FBI agents to arrest theives in suburban Chicago or the remote Mohave desert? Would you rather have a special agent from the FBI ask you why you are taking photographs of a train or a railroad special agent. I personally would rather have the latter.