It's from a time when the country was more sparse. A normal citizen can make arrests only with proof of a crime, in some very important situations like theft or

It's from a time when the country was more sparse. A normal citizen can make arrests only with proof of a crime, in some very important situations like theft or trespass you'd like to be able to arrest on suspicion. If anything these hyper-specific forces tend to be more professional that local police forces.