If you've got old people who want to talk, can't you connect them with each other and not have to pay people to talk to them? Then you can charge a lower price since it's merely a matchmaking service.

Or is the payment an incentive for someone to be a willing audience to be talked at? I think that paying people is an implicit admission that the benefit of the conversation is pretty one-sided.

Others have noted that the pay/hour is actually pretty reasonable, but unless it's a video call I can see the "volunteers" just going "mm hmm, wow, that's interesting" at every break in the conversation and not actually engaging in the conversation. The more sophisticated volunteers might even set up a soundboard to do this. I have a hard time believing that you'll get a lot of quality conversationalists to sign up.