No, penetration aids don't need any control system, they're literally just dumb pieces of metal. Of course they won't explode or be accurate at all, but that's irrelevant to soaking up interceptors which need to be a launched well before impact.
It's literally sending up some of the most sophisticated vehicles ever made by mankind to defeat mostly chunks of metal. Hence why even the US can't afford it in any meaningful quantities.
Everything on an interceptor is much more expensive because of the much higher performance requirements. But the fuel and structure will still be a lot cheaper compared to the rest of system.
Satellites in LEO and MEO can be destroyed with reasonably affordable conventional missiles nowadays, and it's impossible to hide or maneuver satellites in the few minutes it takes a missile to get up, so it doesn't really make sense to expect that any such system will survive long enough to do anything in a hot war scenario.
Hence why nobody really wants to weaponize space, spending money on military systems that have no survivability isn't very attractive.
It's literally sending up some of the most sophisticated vehicles ever made by mankind to defeat mostly chunks of metal. Hence why even the US can't afford it in any meaningful quantities.
Everything on an interceptor is much more expensive because of the much higher performance requirements. But the fuel and structure will still be a lot cheaper compared to the rest of system.