It's certainly not 15% marketshare among premium corporate users. I bet if you condition on the company spending at least $700/unit on laptops for their employees, Apple's marketshare is more like 70%.
Did you miss a digit there? Seems like a very low bar. Every non-tech company I am aware of spends well more than that on laptops for very basic computer uses.
Where I work, Apple is a choice, but very few people have them. The only people I know who go for them are designers.
I know both my GP doctor (hospital) and specialty doctor (private practice) use bog standard midrange Windows laptops that can't possibly cost more than $700. Once you get past the $700 mark you're entering premium territory like XPS/Spectre/ThinkPad.
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