Some RC excavators can move loose material, but digging capability varies dramatically. Machine weight, actuator strength, bucket geometry, traction and soil condition all matter.
Loose material vs compacted ground
Sandbox material and loose dry soil are much easier than compacted earth. Small toy excavators should not be judged against hydraulic hobby equipment.
Machine stability
The undercarriage must resist the forces created by the boom and bucket. Weight distribution and track grip affect whether the machine digs or simply slides.
Use realistic expectations
A product page should describe the evidence for its intended terrain instead of making a universal “digs real dirt” promise.