I think some "receiver" capacity is in the design of the condenser. Or the condenser can hold the entire refrigerant charge. If memory serves I've serviced a few freezers with TXV's and no receiver that still had a liquid valve that allowed you to pump it down for service procedures. The condensers were able to hold the entire system charge. Ditto with A/C units.
They make refrigerators for a market that is saturated with cheap equipment, built with corner cutting in mind. Refrigerant is expensive, use less and you save money. Even with a receiver they would put in just enough for it to work, so might as well cut the receiver out and save that coin too.
Just my opinion. Can't imagine that anything other than cost drives the use of critical charge systems with TXVs.
The receiver is not for pump down nessisarily. It's needed when additional flooding charge is required for low ambient operation. If ambient is controlled, as pointed out earlier, the cond coil can hold the entire charge during pump down. A lot of your reach in equipment may not have or need a receiver. Self contained reach in equipment any way. Remotes may need them even if cond is in controlled ambient depending on lineset.
The condensing units are factory. From 1984 and still kicking. I have at least eight of these older units configered with recievers and cap tubes.
I have never seen a factory condensing unit use a receiver with a cap tube system. How about you get us some model numbers and we do some investigating ? Or might you be seeing cap tubes coming from a distributor ?
Depends on how the TXV sits relative to the condensor, and what the capacity is. Plenty of low charge systems have no reciever. Like someone mentioned earlier, many AC's don't have recievers. As long as there is a good supply of liquid refrigerant consistantly between the TXV and the condenser, it will still function well.