Careful - after iOS 12 that defaults to calling 911 for you (while also locking your device). You can change that in the settings though.

Correct, I just did this yesterday while idly fidgeting around with my phone. Fortunately I cancelled it in time to avoid creating a false alarm. Glad to hear it can be turned off, doing that now. WTF were they thinking, making it so easy to trigger by accident?

(Edit: OK, I'm confused. There doesn't seem to be an option to disable the emergency trigger entirely, but there's an "Auto Call" slider whose relationship to the feature is unclear. This slider is turned off, yet the phone still went into emergency mode when I clicked the button a few times. What a half-assed feature, sadly typical of Apple's work lately.)

They made it easy to trigger so that people can use it as a panic button. That was a customer request.

Apple gets a lot of customer requests, 99.9% of which they ignore, and 95% of which they should ignore. This was a funny one for them to select for implementation.