The OP's title is "How dangerous is police work" or some shade of that. It doesn't have to be the world's most dangerous job for it to be a dangerous one, and dangerous enough. I don't see nearly as many janitors and such lose their lives in their line of work. Sorry, it's not just not classified as a dangerous job for a reason. Thankless, yeah, it is.. but not dangerous.
No one is forced to work any profession.. people don't DO it for the thanks. And being a police officer is NOT something you become for the money. The money alone is NOT worth the time and effort the job requires in comparison to other professions. Regardless, recognizing the people that help your day to day life behind the scenes should warrant some sort of appreciation, even if you don't particularly appreciate the way they're helping. It harms no one to do it. It has a heavy influential positive outcome on people and their morale, job performance, and such. And when your job involves dealing with anything from hurt, broken people to scumbags, making sure they know they're actually influencing things in a positive light is extremely important. It keeps people from burning out and seeing the negative. And it bring some recognition and light onto what actually goes on each day in the lives of cops, and that's important--because they aren't just that guy that pulls you over when you're speeding. They've got bigger roles to play. That's why it needs to be used. Because there are few alternatives with as many positive benefits vs costs ratios.All that aside, why does that even matter? Why does anyone need to be thanked simply for doing a job they chose to do? No one is forced to become a police officer.
You definitely don't need to thank them yourself. But as a society? It is important to recognize others--and the more dangerous and influential, the more spotlight, good and bad. It's why we have awards, and ceremonies, and parties.. we recognize those around us all the time. It's integrated in all around us. It seems a little... silly to have to explain that.