Well Java is one of those languages that a lot of people don't like working with because of it's verbosity and is overkill for a lot of simple applications. People to tend to favor Python for simple things. Java is best suited for Banks and high-level web applications for big corporations which is why Java developers make more than 100k at least.

Same reason, why policemen get lower salaries than Java developers. There are many people who want to be and become policemen.