And the roads themselves are good in NL (huge contrast when I moved to Montreal, where we'd have a metal mesh underneath bridges to catch falling concrete)
In the US, we have many more lights due to the road layout (grid). There are more than 3200 signaled intersections in my county in California alone despite being 1/14th of the land area of the NL.
The robot also estimates that there are 300,000 signaled intersections in the US. We honestly don't know how many there are because they are all operated by different agencies.
For US arterial roads iVRI has limited benefit. So the focus in the US has been on V2X development which focuses more on crash avoidance and has much higher installation costs due to latency requirements. In the end there's a lot of low hanging fruit here in the US if signals could just be retimed.
https://transportationops.org/publications/2012-national-tra...
NL has one procurement entity. In the US there is no single coordinating entity to standardize traffic lights. Each state standardizes its own lights and then each municipality handles its own procurement.
Lowering the number of traffic lights in and of itself is a good idea. Overpasses and (turbo)roundabouts, clever right of way, better road hierarchy; there are lots of alternatives that may provide better throughput and more safety for a given intersection.
The Netherlands as a country with 18M inhabitants is best compared to a big city with the surrounding metro area.
There's an annoying one near me at the bottom of a hill where anyone approaching from the sidestreet will ruin the descent on bicycle, even if they were turning right (from a dedicated turn lane) and didn't need the light to change for them at all. Another is a former police station now used as a park facility. Cars entering the parking lot only need to barely brush over the sensor and the light changes instantly for no reason because they never reprogrammed the light when the police left.