Tracks are excellent for this use case because they have a very large footprint, which makes it near impossible to tilt, and they are also very smooth so it doesn't feel like you're driving up stairs, so it just feels like you're driving up a ramp because they're so flat and they adapt to the stair profile. So it doesn't matter if the stair is wooden or metal or glass, the tracks they grip and there's no danger of slipping.