I don't think it's the responsibility of the police to protect you anywhere. By responsibility I mean, if you are not protected you can hold the police legally responsible.
Can you imagine how many police we'd need if there were an obligation to protect everyone at all times? There isn't a country on Earth with police forces that large.
There isn't a country with enough police to protect everyone from physical harm caused by others at nearly all times (statistically speaking)? I doubt it.
And I doubt OP was speaking about those times when the country is entirely on fire or the police department has been nuked. Rather, I think the point is that the police will do anything they reasonably can do to help.
the police are not obligated to help you in the US, this has been the subject of at least 2 supreme court cases.