Some percentage of the users may be OK with not knowing if there are bots. Get a few attractive "people" to match with you, get a self esteem boost and move on with your day. And there is the lottery element. What if this one isn't a bot and actually picked me out of the thousands of other options.
Tinder is money printing machine via subscriptions. It does not give a two cents about daily usage metrics popular among VC supported or advertiser centric companies that don't have a product its users want to pay for.
