F1 is an ecosystem in which the competitors agree to a set of rules as a prerequisite of participating. Among the guiding principles of the rules are "limit sp

F1 is an ecosystem in which the competitors agree to a set of rules as a prerequisite of participating. Among the guiding principles of the rules are "limit spending on aspects that don't meaningfully affect the competition" and "when possible, make it easy to enforce the other rules". Using a single, common ECU (which is both complicated to manufacture and doesn't directly influence performance [0]) saves all the teams (bar McLaren) from having to go down a rabbit hole of doing semiconductor design and manufacturing and makes it easy for the governing body to enforce rules about how the ECU is configured. [0] How the ECU is configured does, but the ECU itself doesn't