Vision is "easy": What I see is what you see is what the machine sees.
A machine shows us what it sees and we can verify that it is working correctly, with a glance.
How would we verify that a machine smells or tastes "correctly"?
I'm no olfactory biochemist, but that sounds like science-fiction to me. The, er, reference implementation we're talking about is advanced nanotechnology we don't fully understand.
While we can do stuff like mass-spectrography, that involves destroying complex chemicals and converting them to smaller fragments we can tally, and then guessing at possible configurations they might have originally had.
If someone had a device that could simply tell you the exact chemical formulas of all molecules of any kind in a sample, it would be used everywhere and they would be very rich.
This would be a very large machine and you would need to provide a sample to it in a test tube or similar manner. Automated blood analyzers in hospitals are maybe the closest thing to a such device.
I dont say such machines don't exist, but for my taste (pun intended) the solutions all lack something, either long term stability or having a second source supplier or being able to classify a reasonable amount of tastes or being able to distinguish between two tastes (or lacking all those things together).