In my experience, the drop-down lists for pre-American-Revolution places include county names, but it's sometimes not clear that they are counties, because the county names don't include the word "County."
Most of the areas I've researched seem to have had some sort of a functioning county government during the colonial era, although the counties didn't necessarily exist from the time of initial settlement.
One issue I've encountered regarding pre-Revolution counties is that the dropdown list doesn't always reflect changes in the county for a particular community. For example, Kinderhook and Claverack, New York, were in Albany County before 1786, when Columbia County was formed, but the dropdown list treats them as always having been in Columbia County. That's a problem, because researchers looking for early records from those places may need to look in Albany County.