You may have an inflated sense of what a tower is for, and whether Europeans are better at it than Americans or v.v. Air traffic control (at least in the US) h

You may have an inflated sense of what a tower is for, and whether Europeans are better at it than Americans or v.v. Air traffic control (at least in the US) has the purpose of ensuring separation of air traffic. That is, to help ensure that aircraft do not hit each other, by coordinating when there could be conflicts. They do not primarily exist for (or were not at least created for the purpose of) helping aircraft fundamentally navigate and or avoid non-aircraft obstacles. Or controlling an aircraft's every permissible action in the air. So, if an airfield has little traffic, in general or such as in off-hours, there may be no tower, or the tower may be unmanned. Aircraft then are responsible for coordinating themselves by announcing their activities, and taking the observation of the airport conditions into their own responsibility. It may be you believe that because European airspace is a bit denser, and in general the airports with scheduled commercial service are busier because of the density. But as others noted, there are uncontrolled/untowered airports just as in the US.