Sigh - Any resourced and competent police or security force should be able to catch or deter thieves that are stealing packages from the same location . Additionally, mail theft laws which include prison as a consequence should be extended to package thefts if they don't already cover them.
I imagine this will get sorted since Buffett both invests in Union Pacific and provides insurance. He famously doesn't get involved in the companies in which he invests, but I imagine his people could shoot over a question like, "why is this happening?"
It looks like Buffett owned Union Pacific shares a while back, but sold them in 2009 so that they could buy BNSF.