He says Paypal is in C++. That used to be true 10 years ago, but is no longer true. Paypal's back end is written in Java.
Basically this is a table with cherry picked software projects where anything that isn't in ASM, C, C++, or Java is lumped into "Other". I don't know why anyone would create this useless page. It's in a style that honestly suggests "pre-internet" where all your knowledge came from curated sources. Nobody needs to curate this list.
It is not only that. There is a huge bias towards products written in C or C++. E.g. there are niche not-production-ready-yet products like ScyllaDB listed, but many popular, bigger and mature databases like HBase, ElasticSearch, Solr, H2, HSQLDB or Derby written in Java are missing.
TL;DR Pretty much everything is in C/C++ unless it is Oracle/Apache related which also has some Java or Microsoft who use C# for a few things (but not much).
It has a bias because it choose programs that you can install. It's a good category, but it left some applications out. For example GMail, Candycrush, Facebook, ...
Gmail is equivalent to MS Outlook, so I think it's fair to include both.
Candycrush is implicitly considered in a note in the "games" category, I don't know how would be a fair way to count the installable games, flash games, javascript games, android games, Appstore games, ...
Facebook is in another category (can we put it with Webpress or something). It's more a webpage than an application, but the difference is not so big.
To be fair - the installable programs are quite old. C# is probably the best choice for Windows development if someone would care to write a desktop app today...
I would guess that Javascript and COBOL have a fair share of all existing code that is not C, C++ or Java.
Maybe the big five has 85-90% of all code ever written?
Looks like C++ rules systems software, the momentum has to be tremendous. It'll be interesting if Rust is listed here someday. I'm guessing the overall library and tooling ecosystem for C++ is going to be difficult to match in any short timescale.
The page misreports some C-based or C-with-classes-based software as C++. E.g. Windows kernel and drivers is written in C, with only some userland stuff written in C++ (and other languages like C#). Yet the page states it uses mostly C++ and a little C. This is really ridiculous C++ fanboyism.
OO, constants, exceptions, stronger typing e.g. templates and associated libraries of containers, booleans, references, new operator, don't have to decl every local var at a top of function etc. For many of us, C++ was a dramatically nicer experience for building very large code bases.
There are "C programmers" who are really using "C++ in C style" and don't realise what C++ brought to the table. Some C++ features have now been included into C.
It's not odd if you consider the general theme of the list. It's not as if it's meant to be an exhaustive list of programs and which languages they're written in; in that case there would be more languages than 5 + "other". Riak is not on the radar of the author, whereas K3B / Nero Burning ROM is. Why that is seems fairly obvious.
Basically this is a table with cherry picked software projects where anything that isn't in ASM, C, C++, or Java is lumped into "Other". I don't know why anyone would create this useless page. It's in a style that honestly suggests "pre-internet" where all your knowledge came from curated sources. Nobody needs to curate this list.