Your assumption is correct. It's on the Rabo website [broken link removed].
It's not because Rabo aren't Irish. It's because each fund is a separate offshore entity so by switching from one to another, you're selling one and buying the other, which is two separate transactions.
Domestic funds allow you to switch internally between funds and Exit Tax will only be calculated on the gain made on your overall investment. However, if you switch providers, e.g. you cash in Irish Life funds at a loss and buy into New Ireland with the proceeds, you can't offset your Irish Life loss against any subsequent gains made by New Ireland.