You obviously don't live anywhere it snows if you think running out of washer fluid can't be catastrophic.
Right, thanks to global warming, it hasn't snowed in Minnesota for many decades.
Never had an issue when run out of wiper fluid on older vehicles which didn't have sensors. When it happens I pull over and refill from the bottle in the trunk. I like that newer vehicles have sensors for when it's low, it's a great convenience. But not really
required. Now, having the wiper motor on my Mustang stop working ... that's a different story.
And the other components can develop leaks. As far as requiring frequent changes, a properly maintained engine shouldn't burn enough oil between changes for it to be an issue. So frequent changes doesn't help your argument. if you engine does burn that much oil, then you should be able to keep track of that easily enough with the sensor, and know if it's reading accurate or not.
What was my argument again? Oh yeah, that it sort of makes sense that non-engine fluids don't have sensors.
Engine oil is changed much more frequently (~ 5k) than transmission, xfer and diff's (~50k). There just aren't as many reasons to frequently check the non-engine fluids because we don't often change them, and leaks present visual clues. Anyone prone to check their xfer/diff/trans fluids are also likely to actually look at the components.
I would argue that a properly maintained
and engineered engine shouldn't consume enough oil between changes for it to be an issue, and most of us would agree that any significant consumption would be problematic. However, the manufacturers have documented that some oil consumption is normal, especially when they prescribe 10k OCI's. It's usually something like "Less than 1L per 1000km" or "1qt per 1000 miles" before they'll tackle it as a warranty issue. Personally I feel this is a cop-out (and I don't go 10k between changes).
But anyways, back when I had an Audi (which had a tube but no dipstick, and could be added later) there wasn't a month that went by with a new forum member complaining that they overfilled and killed their engine because the sensors returned an incorrectly low level. There is definitely a good reason to have a dipstick, but I wouldn't consider it a requirement in choosing an engine.