In fact, Square invested a lot in infrastructure that was pretty impressive compared to other companies of a similar size. We're talking 800-1200 people and they had a single common custom deployment system that had been built before Docker was a thing, and later replaced that with a new in house system (p2) based on containers while I was there. They had a common custom CI system that all services used, and that actually worked quite well (much nicer than Jenkins which was common at the time). And Square really only had 3 languages that were acceptable to use for services (Java, Ruby, and Golang; node.js being phased out). I remember interviewing people at other larger companies and finding they didn't have things we had at Square in 2014, like a common way of configuring and registering services, or an easy way to see what's running on a particular box, or service-to-service ACLs, or a tool to coordinate online schema changes. Square even built their own S2S RPC protocol based on protobufs, and went on to participate in the design of gRPC.
Maybe it's changed since then, I don't know. But the culture was pretty solid when I was there. And the plateng team ran multiple DC failover tests of our service while I worked there.