More like all languages are not equally easy to test. Just like all languages are not equally easy to write. It's incredibly easy to write mocks/spies in javascript without a single third party library. It's tedious to do that in Java.
There is also a corporate culture of tests that mandates bloated test frameworks, which leads to developers spending more time on writing tests than writing functional code.
That depends on if you are shipping tests to customers. Most companies are shipping code, not tests, so time spent on test is time not spent on code. You only want tests that make code easier to write.
You’re not just shipping code, you’re aiming to ship a correct program right? And tests are a part of that and will be on the list of risks the customer may be concerned about. It’s not just about making code easier, it’s about showing the code works as expected.
There is also a corporate culture of tests that mandates bloated test frameworks, which leads to developers spending more time on writing tests than writing functional code.