Moats, as noted in Google's "We Have no Moat, and Neither Does OpenAI" memo that made the discussion of moats relevant in AI circles, has a specific economic definition.
Switching costs only make sense to talk about for fully online businesses. The "switching cost" for McDonalds depends heavily on whether there's a Burger King nearby. If there isn't then your "switching cost" might now be a 30 minute drive, which is very much a moat.
That's not entirely true. They have a 'infinite' product moat - no one can reproduce a big mac. Essentially every AI model is now 'the same' (queue debate on this). The only way they can build a moat is by adding features beyond the model that lock people in.