A restaurant with a dining room can treat a delivery app as incremental revenue and shrug at the commission. A takeaway kitchen with no other channel is paying that same roughly 30% cut on the majority of its sales, which turns a marketing decision into a margin decision fast.
Square's Plus plan at $49 a location a month and Toast's ordering module at around $75 both give you a branded ordering page with a materially lower cost than a marketplace commission, and both route the order into the same kitchen queue as everything else rather than a separate tablet. The trade-off is discovery: your own page only gets found by people who already know you, while a marketplace puts you in front of people who do not.
Most operators in this category end up running both, and the sensible way to think about the marketplace commission is as paid advertising with a very high cost per acquisition, worth it for new customers, worth actively discouraging for repeat ones you can move to your own page instead.