@ehBeth,
Yeh, they're on purpose not airtight. The proof can be found on the surrounding counter, depending on how full the pot is.
Confusing things more, when I make things in either a slow cooker or used to with a rice cooker, it wasn't about vapor (vapour), except that with rice in rice cooker (or my le crueset), it was a no no to lift the lid - so that vapor did have some participation in the cooking.
I have tended to not obey not ever opening the lid, being a cooking brat.