LIDAR also does work great in the rain - provided you have multiple LIDAR units (e.g. Ford's snow-proof sensor array: https://qz.com/637509/driverless-cars-have-a-new-way-to-navi... ).
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.
That said, I think it's disingenuous of Tesla to call their system "autopilot" or imply autonomy of any kind when talking about their system. I will call something autopilot when it can drive me from door to door without me touching the wheel, in less than friendly weather conditions. Not drive in a straight line where it never rains.
It's true that a careful, experienced driver will typically recognise a rapidly emerging hazard as much as several tenths of a second faster than a novice, giving them significantly more time and space to react. However, a careful, experienced driver will also anticipate places where there are likely to be hazards and adjust their driving style to compensate.
Does a self-driving car know that there's a park just round the corner and it's half an hour after the local kids came out of school, thus increasing the risk of a child chasing a ball into the road?
Does a self-driving car understand that the group of people standing quite near the road up ahead are outside a bar at 11:30pm and thus quite likely to be drunk and suddenly stagger into the road?
Does a self-driving car know about the pothole in the cycle lane that you had to avoid while riding into town yesterday, and anticipate that anyone riding in that cycle lane today may move out into the main traffic lane without warning to go around it?
Does a self-driving car know that the news last night reported on a local black spot for "accidents" caused by people wanting to make fake insurance claims, and decide to take another route that is a little slower but avoids that black spot?
Better sensors, fast data processing, and the ability to monitor all sensors all the time are big advantages, for sure, but these things mostly support reactive behaviour. I've seen nothing so far to suggest that the better reactions currently outweigh proactively avoiding or mitigating these kinds of hazards in the first place. Obviously that might change in any number of ways in the future, but we seem to be a long, long way from that point yet.
If you seriously want to play the inane game of "well if a human doesn't have it then a Tesla doesn't need it" then let's play that game and talk about the things humans have that the Tesla lacks.
What's interesting about human's vision system is that the human eyeball is, relatively speaking, poor. We have digital cameras far better than that already. It is what the human brain that does with that raw data which makes us, as a species, thrive. Most of what we believe we "see" we never actually see, our brain fills in the gaps dynamically and infers information over time.
So this human processing ability, much of it automated rather than conscious, is totally relevant if you want to have this "Tesla Vs. human" debate. It is also why Lidar might be needed to make up the massive shortfall in a Tesla's processing ability relative to the human brain.
But hey, you want to keep to the "but HUMANS don't need it" then I ask where is my 38 petaflops and 1 TB of memory...
Teslas have multiple radars for judging distance and multiple cameras that are used for stereo disparity. Also human 38 teraflops is not the same as nvidia teraflops.
I am not saying teslas are better than humans, I'm just saying teslas can drive on I5 highway from Vancouver to Mexico better than I can.
Also Lidars are really really expensive, I applaud Tesla and commaai for breaking major ground just with cameras. Convolutional neural nets have being doing phenomenal things in the past few years.
You can find other figures, but many are in the petaflop range, well above what could be realistically installed in a vehicle.