i can't speak to the others but banking and healthcare is virtually all java top to bottom. The big healthcare EMR/EHR systems are Java and every bank i've ever worked with (i use to do a lot of integrations with the big banks) was all Java. I have friends in those areas and whenever they start up a new project it's still always Java since that's where their skills are and what's on the "approved tech." list.

in my healthcare experience (claims processing, medtech) Java existed for sure but it was always as a "legacy" system they were moving away from.

What were they moving towards?

claims processing - TypeScript, lots of ETL tools with Go.

medtech - .NET and TypeScript.

We embedded angular in our old Java client for hospitals. The user thinks he just opens a new window, but it's chrome in Java, which opens angular frontend, for our Java backend.

Until quite recently, the reasonably feature complete open source libraries available for things like DICOM or HL7 were old C/C++ libraries, Java, and C#. That often created a choice between Java and C#. People not doing Windows based development tend not to be interested in C#.

Cross platform C# is certainly getting huge in healthcare and medtech recently though.

Is it? My experience from 2014 - 2018, was that C# was only used in the lifesciences software for Windows, and as wrappers around device drivers mostly written in COM.

Everything that was done on the backend side was done in Java, although there were some exceptions for .NET deployments.

So we ended up with mixed skills teams where depending on the ticket, you would be coding Java or C#.

IME this decade a lot of people are using C# for Azure 'serverless' deployments.

First, they do. Second, most software is not only not produced by software startups, it's not even produced by software companies. Do you know how much software a bank, or a credit card company, or a telecom provider, or a car manufacturer (like BMW), or a shipping company (like FedEx), or a defence company (like Boeing), or a large retailer (like Walmart) write in house?

Wasn't the discussion about greenfield projects? Or by greenfield do you mean internal greenfield projects at existing companies that already use Java?

Greenfield doesn't imply startups, does it?

Greenfield, in my mind, implies "we are not taking any historical factors into account and just pick the best one for the task."

"We are a Java house" is not a Greenfield thing. It's picking what you already use internally.

I used to work on bank, and their java code was very bad, although it works as they have been using same code for 30 years lol.

I've never worked at a place where the code was "good".

From what I see, most software being created in these spaces isn’t made by startups.

If they want to target Android customers, most likely they have to anyway.