Why aren't metering valves used on all vehicles?

Metering valves are not used on all vehicles primarily due to cost and complexity considerations. While they can enhance braking performance by controlling fluid flow, their installation adds to manufacturing expenses and maintenance requirements. Additionally, many vehicles are designed for standard braking systems that meet safety and performance needs without the added sophistication of metering valves. As a result, manufacturers often opt for simpler, more cost-effective solutions.