Because of the fairly unique requirements of their setup (I have heard them describe the LHC, with its storage ring of about 30km, as doing “10,000 experiments

Because of the fairly unique requirements of their setup (I have heard them describe the LHC, with its storage ring of about 30km, as doing “10,000 experiments per second”. They throw away most of their measurements within a ms, but still keep about a petabyte each day (https://home.cern/science/computing/storage https://home.cern/science/computing/storage)), they build their own hardware, network, storage arrays, etc. I think that builds a culture where it’s normal to build your own tooling. It also may help that they have huge budgets, making it relatively cheap to develop this kind of stuff.