Some sort of gas injection system is essentially universal in rocketry since you need something to maintain tank pressure as you use the fuel in the tank. The

Some sort of gas injection system is essentially universal in rocketry since you need something to maintain tank pressure as you use the fuel in the tank. The helium vessels aren't always COPVs, sometimes it comes from outside the tank, and some rockets use something called autogenous pressurization where propellant is heated to gas to take up that extra space. And some rockets manage without pressurization entirely though I believe only very low performance ones. SpaceX hasn't flow anywhere close to 700 flights but a lot of testing would involve fuel loading so the 700 figure sounds high but not unreasonably high to me.