Retail businesses spend a lot of effort manipulating the customer experience using A/B testing: they understand that there's a time and information asymmetry between business and consumer, and so they go to great lengths to withhold pertinent information so that the consumer can't compare prices before shopping. A standard technique is to advertise one price, then tack on unadvertised "fees" that only appear later in the checkout process once a consumer has invested significant time and effort into the order. An even uglier one (hey DoorDash) is to advertise a "delivery fee" up front and then later present a separate line item labeled "taxes and fees" that contains a second portion of the delivery fee (previously unadvertised and also labeled in a deceptive way.)
If you want to let businesses mislead consumers without limit, then you might as well build a society that legalizes false or fraudulent advertising entirely: that's close to what these businesses are doing here.
The price of the pizza goes to the restaurants, the delivery fee goes to the driver (mostly, I hope), and the "online convenience fee" goes to the business running the online ordering system. It all works out.
I don't think I've ever [edit: should read "recently", I surely saw some early ones that didn't] seen one that doesn't specify that the driver doesn't get the money. Presumably because when they (most pizza delivery places do this now, plus I think Jimmy Johns does it, probably others too) first started adding those fees some years back, people assumed it was for the driver and stopped tipping, since it's usually about as much as a decent tip would be.
Ever-rising, often-sneaky (different prices for delivery, much worse coupons for delivery vs. pick-up) increases in delivery costs have me thinking like my parents used to, and rarely ordering delivery anymore. There was a golden age in the late 90s and early '00s when delivery was pretty damn cheap, basically just $3-5 for a tip. It's over.
It's opportunistic to charge more in this way, it's actually tacking the cost savings of coupons on at checkout, which also makes it a rather deceptive practice, whereas, the simply could have increased the cost of their pizza margins, but these days cost schemes online have become the norm on top of taxes and tips. It's a shameful business practice that not enough people call out.