Visual cameras can be blinded fairly easily - even high-end cameras - simply point such a camera at the sun and try to make out a cloud in the sky. If Tesla were using true high-dynamic-range cameras (e.g. Oversampled binary imagers) then I would be more confident - but Tesla isn't saying that they are - and if they really were they would definitely boast about it.
What I like about LIDAR is that it will never give you false-negative data regarding object proximity (i.e. it will never tell you an obstruction in the road is not there) but visual-only cameras can be fooled very easily and definitely can give you false-negatives regarding road obstructions.
It seems inherently less safe to rely on a more homogeneous sensor array: conversely it makes sense to use as many different types of sensor as possible to ensure your design isn't susceptible to being brought down thanks to a weakness in your predominant sensor type.
