The cafeteria itself is a large scale enterprise, wholly enclosed inside the larger scale enterprise.
...and these days, someone has to justify their continued employment, hence guaranteeing that said app and its related systems will be subjected to constant trendchasing and the inevitable resultant enshittification. It's otherwise perfectly possible to create such an ordering system that will keep working with next to no attention, which is why the most stable and reliable systems I've worked with were created by someone who didn't want to have to work on it more than once.
Which one is it? And, more importantly, why not name it?
And then, since you have all these integrated functions, you can spend headcount optimizing datacenter spend down. Hire a team to re-write PHP to make it faster literally pays for itself. Or kernel engineers. Or even HW engineers and power generation. And on the product side, you can do lots of experiments where a 1% improvement in ad revenue pays like the entire department's wages for the year. So you do a lot of them, and the winners cover the cost of the losers. And you hire teams to build software to run more experiments faster and more correctly.
The brakes on this "flywheel of success" is the diseconomies of scale outweighing the economies. When the costs of communicating and negotiation are higher internally than those external contracts you previously subsumed. When you have two teams writing their own database engine competing (with suppliers!) for the same hires. When your datacenter plans outpace industrial power generation plans. When your management spins up secret teams to launch virtual reality products with no legs.