When machines were cash only, there was a big box of cash sitting unguarded on a lonely corner at 3am...
It's not a fast, discreet, or easy process.
They are big and bulky and heavy and all that work for, what, $80? Junkies aren’t usually that coordinated to pull this off.
$80 sitting easy is great for a junkie. But requiring multiple steps and special equipment may as well be a voyage to the moon.
For proper criminals who can plan and procure equipment, $80 probably isn’t enticing.
And that's assuming your vending machine isn't using some standard key you can just outright buy on ebay.