There's stuff horses can do better than even the best of our current technology. Where that stuff matters, horses are still employed.

Where cars displaced horses, it's because they're strictly better in a larger sense. On the city streets, maybe a car is louder than a horse, but it's also cheaper to make, easier to feed, and doesn't shit all over the place (which was a real problem with scaling up horse use in the 19th century!). Sure, cars shit into the air, but it's a more manageable problem (even if mostly by ignoring it - gaseous emissions can be ignored, literal horse shit on the streets can't).

And then, car as a platform expands to cover use cases horses never could. They can be made faster, safer, bigger, adapted to all kinds of terrain. The heart of the car - its engine - can be routed to power tool attachments, giving you everything from garbage trucks to earth movers, cranes, diggers, to tanks; it can be also taken outside and used as a generator to power equipment or buildings. That same engine can be put in a different frame to give you flying machines, or scaled up to give you ships that can carry people, cars, tanks, planes or containers by the thousands, across oceans. Or scaled up even more to create power plants supplying electricity to millions of people.

And then, building all that up was intertwined with larger developments in physics, material engineering, and chemistry - the latter of which effectively transformed how our daily lives look like in the span of 50 years. Look at everything around you. All the colors. All the containers. All the stuff you use to keep your house, clothes, and yourself clean. All that is a product of chemical industry, and was invented pretty much within the last 100 years, with no direct equivalent exiting ever before.

This is what it means for evolution accelerating when it moved from genes to information. So sure, horses are still better than stuff we make. The best measure of that advantage is the size of horse population, and how it changed over the years.