This is due to the method of data acquisition. My company also uses cesium (in the browser) for visualization at sub cm level for inspection. Our quality bar is that inspectors have to be able to inspect the grain of the grout between the bricks.

We acquire the data in 3 modes for high buildings, we do low altitude fly over with the 2m drone, then we do facade with the regular drone, and finally we shoot from the ground. We only do ground based lidar, but aerial lidar is improving so maybe that's next. The rest is all high detail photos fed into photogrammetry.

The final results look perfect in cesium, some thin rails might not show up, and windows get a bit funky, but the geometry and the textures load in without a hitch, really cool technology that's so simple in the basis that we built an alternative viewer in Rust+WASM in 3 weeks.