This isn't entirely true.

Baker cells are in a lot of pharmacies that have high(ish) volume, and they vary in size, the last retail pharmacy (Walgreens) I worked at had 83 slots (but 3 were doubles for large pills, so 80 cells). Parata machines are for even higher volume and typically have almost double the baker cells in medications (but break more easily and can't always be fixed by a pharmacy employee).

Walgreens use to (and probably still uses) a scale to weigh, with preset values for the weight of pills. Of course, this is manually set up by corporate so if a drug is new or uncommon it may not have a weight entered which may cause you to manually count.

There exist machines that you literally dump pills straight into and it uses motion sensors to count how many pills have fallen through, giving you a (mostly) accurate count that has absolutely nothing to do with how fast the product moves. There are other types than what I linked, it's just an example, and it's not the one I've used.

All controlled substances are (or should be) double counted by the person counting the medication. Most pharmacists do not double check this, so long as the bottle looks reasonably full and if the quantity is circled and initialed. The count that a pharmacist will do is on CII narcotics, and that is only counting what is left in the bottle to verify that the correct amount is left in the safe. Many techs will just circle the quantity and not actually do the double count.

In essence, most Walgreens don't count your pills because of scales and ADMs. In CVS, many pharmacies have baker cells for the most dispensed 50 or so medications, otherwise they count by hand (unless they have upgraded from when I quit 7 years ago). Some independent pharmacies will buy the infrared counting machine to speed up counting. Most low volume pharmacies count everything by hand.

All this said, it takes less than a minute on average to do the filling portion of the prescription, from the second you pick up the label to having it labeled ready to pass to the pharmacist for final verification if you're actually focused on the task. The majority of the bottle necks I have dealt with are at the pharmacist's end, because nothing can proceed without them.