The issues of GPR in rocky or variable soils and the difficulty of interpretation end up being very limiting to actual usage in my experience. It's pretty difficult to scale in the same way LIDAR can.

It's also common for there to be surface expressions of sites, as long as your signal filtering and sensors are good enough. Even the 1m data the UK publishes has been amazingly useful.

With the data I've seen from modern high end sensors, whew.