Here is how a good boss would rationalize it.

Boss: Hi new Employee, what laptop would you like to use as your daily computer?

Employee: A $700 Dell.

Boss: Are you just saying that to save the company money? Because it's not about the money. I'm paying you $80k a year and I want you to be productive and happy. I want you to pick something you feel good about every time you use it. You will be using this laptop 40+ hours a week for the next 2 years. Don't forget, this is your job and career.

Employee: Hmm. Well, I do prefer Mac to Windows. Is a $2200 15" MacBook Pro retina OK?

Boss: You tell me. The purchase price is a tax write off. I really don't give a shit.