I think I'm really struggling with this as a concept... and maybe it's product-specific.
Obviously food is way, way, way, way more automated now than in the 1990s, both with fresh produce and processed-food. The economies of scale for farms now in comparison is far more efficient, but you're right, there are a ton of other factors involved in pricing.
Televisions are absolutely cheaper... but mobile phones are harder to compare - we might be spending as much or more on the devices themselves and data... but these devices do so much more than in the 1990s and need way more data.
Again, even though automotive factories are way more automated than in the 90s, cars themselves are still a decent percentage of people's expenses... but again, they are safer, more efficient, etc.
I guess where I'm struggling is if technology is deflationary, and I'm sure you're right that it is, but there are other factors like wages, protections, real estate, etc are not deflationary, then how much is the overall effect will be?
Can robotics cause overall deflation if other factors are too inflationary? I guess the real question is... will robotics positively impact my life?