People keep saying this, but the only way to assure there is no collision is to have non-intersecting orbits, but that is not going to work: not enough space.

It's a tell that SpaceX is now lowering the orbits, even though their satellites mostly move in flocks that maintain a formation relative to each other: because the other ways are exhausted.

Of course if they do cause a (low orbit) Kessler syndrom, then they don't have a business any more, and SpaceX will have achieved the opposite of its stated goals.

The major reason to lower these orbits is likely the risk of a terrorist state turning these constellations into a weapon, by willingly causing the Kessler syndrome. SpaceX isn't going to tell you that, just as it doesn't tell you it's the USA's most important military asset.