A couple of things: one is that there is additional legal/compliance stuff to deal with for each additional country (EU might count as one, when it comes to that), but the bigger reason is that we wanted more overlap in working times. It's also less expensive when we do get together in person at headquarters in California (which has typically been 3-4 times a year).

Hiring remote workers at scale is super complex if you want to comply with local laws (and you must). Hiring contractors is easy but if your contractor should be indeed classified as an employee you will be in trouble one day or the other. You have to set up a legal entity in that country/state, provide workers' comp, health benefits, unemployment, comply with various laws on leave, vacation, medical, etc... This is quickly a nightmare and it is why true good remote companies hire only in handful of states/countries.