Short answer: because national platforms charge per transaction forever and own the customer relationship, while a local presence is a fixed annual cost and the customer is yours.
The economics diverge as you grow. A percentage fee per order scales with your success, so the better you do the more you pay, permanently. A fixed annual placement does not.
You do not get the customer. On most national platforms the diner belongs to the platform. You cannot reach them next month without paying again. A local listing, a member deal and a badge build a direct relationship.
Local intent converts better. Someone searching "best seafood in Jacksonville FL" is choosing a restaurant tonight. That is a different, better customer than a national browse.
Category ownership is available locally and is not available nationally. You cannot buy "the" position on a national app. You can be the established name in your category across the 904.
Where the plans fit. Groups with several rooms take Corporate for multiple locations and premium placement. Established names that want to own their category outright, with the strongest placement across the site, take Enterprise. For a restaurant group, that is a rounding error against a year of per-order commission. See current plan prices.
The strategic point: national apps are a channel worth having. They should not be the only place your name exists.