In my experience, this is the rule at US labs, that everybody brings their own laptop. First, computer choice is personal for scientists. People are either Mac or Windows, and nobody wants the least powered computer available, which is what the lab would buy you anyway. A few of us are Linux-only diehards, and most IT departments will not let you change the OS on university-owned equipment. At my university, if you insist, they'll buy you a laptop, but it's going to be the crappiest model of the lineup, and they will install monitoring software, and you need to ask permission to install programs. At another place I used to work at, if you demanded a computer, they'd give you a clapped-out laptop from the recycling stash. Only at MIT did I get a brand new computer to my specs, but that was MIT. I used to get worked up about this being "unfair" of having to buy my own laptops for the benefit of my employer, but in light of the issues listed above, I have no problems spending my own money in the most important tool I use. This is also common in other workplaces, eg car mechanics have to bring their own hand tools when getting hired at a shop, and carpenters bring their own basic carpentry tools when joining a crew.