I can answer part of this, I think:

When Spain sent conquistadors to conquer the New World, they did not raise any militias or colonial armies from locals (In fact, they had spent quite a number of years trying very hard to wipe out local armies). Instead, they used combinations of privateers, mercenaries, and royal troops from Spain to act as a military in the Colonies, with any and all other military needs being improvised by local settlers. The Royal troops spent most of their time fighting other empires (Like those dastardly French and Anglos), while the mercenaries and privateers took care of naval threats and roving bands of marauders inland, though they would deal with other threats as needed, with mercenaries acting as skirmishers and Royals as regulars in situations where a larger army was needed. Otherwise, they never really raised any colonial troops, and they sure as hell never armed the locals they tried so hard to wipe out or assimilate.

The Brits, on the other hand, never stayed in the Americas in any sizable numbers long enough to dictate a colonial levy, outside of Canada (And that was mostly Anglos). Though they made use of local Native American tribes in the French and Indian War and the American Revolution, they never actually enlisted them into the British military system as a colonial unit, but instead used them as an allied auxiliary to their conventional forces (As did the fledgling US). So even then, they never raised non-Anglo colonial units in the Americas in any sizable number.