I’m tired of hearing the knee-jerk “we need a budget cap” response. It would never work for any number of reasons.
One example: how do you impose a fair spending limit on engine manufacturers who build power plants for different numbers of teams? If Mercedes supply four teams and Ferrari three, do Mercedes get to spend 33% more? That doesn’t work because you can’t differentiate between what is spent on research and development and what is spent on construction.
The budget cap is an easy answer which after a moment’s inspection turns out to be riddled with flaws, any one of them enough to compromise it totally. If having a budget cap was realistic we’d have one already.
And even if it did work, you could never convince all the other teams that it was being enforced. So there would be constant innuendo that one team (probably the one that was winning) was spending more than they were allowed to.