Yes, good point Andrew. I've read that there are three tiers in quality or regulation in ETA - never heard the same about Sellita. If so, I would expect that the cheaper the watch the lower the quality of mech.
I am no expert though, I am still learning about watch manufacture. It is annoying that the tier of movement often is not described in a watch's description.
I have a German watch with a basic Sellita SW-200 mech (but with in-house manufacture) that keeps COSC time so I don't get my panties in a twist if a watch has Sellita or ETA.