That's due to network effects, not because they're operating a two-sided marketplace. And then you list an example where that moat failed (Argentina - and it's not just Argentina).
I suspect that on this particular market, network effects won't have as strong of an effect and the local players have better market insight since they're far closer to the customer.
Two-sided markets are kind of like Willie Sutton's banks. The buyers have to go to, say, Amazon, because that's where the products are. The sellers have to go to Amazon because that's where the buyers are. Amazon does whatever they think they can get away with to keep those relationships exclusive, which is the genius of Fulfilled by Amazon.
I suspect that you're right about the food delivery market. Probably most of the VCs investing in it also suspect you're right. They just aren't sure.
BTW I had to upvote your comment because some dumb fuck downvoted it.
(And, as eru points out, they might be able to establish a regulatory moat to prevent any new entrants from arising once they're established, like the drug and medical device companies. Did you know the first clinical implantation of a cardiac pacemaker was in 01958, only two years after the transistor was invented? The patient died—in 02001, 43 years later. How long do you think it takes an incrementally improved new pacemaker design to get regulatory approval today? Much less a totally new kind of medical device?)
Keep in mind, though, that "VCs are betting" doesn't mean that the VCs think this is the most likely outcome, even the ones who did invest. It just means they think it's sufficiently plausible that if it does happen they want to own a piece of it.