system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it easier to get a job when you already have a job?

I've heard this countless times, written in articles and from recruiting professionals. 

Every time I've been on an interview, they ask me when I'd be able to start. When I give them a date two to four weeks away, their face always drops and I can tell they're no longer considering me because they need someone sooner than that. I know that my personal anecdote doesn't invalidate something that's known to be true but of the many interviews I've been on, I've only found that having a job already is cumbersome to whoever you're interviewing with.
gpt
It's easier to get a job when to have a job because you're in a stronger negotiating position. You don't have to have the job, you already have one.

Also, if you encounter an employer that is loses interest because you can't start for two weeks, you should feel lucky. You're dodging a bullet. This is an indication that the place has high turnover and they value getting a warm body quickly more than getting the right person.

Then you have to think to yourself... "there must be a reason why they have that kind of turnover." Any reason you come up with is likely to be a reason you'd want to work somewhere else.

No good employer will have any problem with waiting 2-4 weeks to bring on a good employee.