As is often the case with information and damned lies there is no 'standard' police crew of two in the USA.
In many states [Texas for one] the crew is the driver and he picks up his eyes from some greenhorn cop on the ground. The basis of that may have been under-performing aircraft types, its easier to deliver a distance with only one on board, anyway they look to alter that and move up to two crew because the system does not work too well and the newer aircraft perform better.
In a large number of states [ok, the largest group] there are two people up front. Either a civvie driver and a TFO, or a sworn pilot and a TFO, or two pilots operating turn about as pilot or TFO. They look to alter that and move up to three crew when they can and the money allows because many of them look up to UK policing which is still seen as pretty good despite the current 'difficulties.'
A few states have a 'standard' crew of three, two pilots and a TFO.
And then there is Europe...... why does no one mention Europe and take a wholly different set of rules [as in the USA] on which to base the critique?
Numerically most US aircraft are pretty much incapable of carrying a complement of three.... the OH-6 and OH-58 are getting to be older than me [and that takes some doing] but they still hold sway and push US crewing towards "single pilot delivery to scene ....."