In the mid-1970s, when I first dove into my picture framing business, I used a Stanley hand miter saw. It had a reputation for accuracy, but it was still not accurate enough for use with pre-finished molding. For that, we used a Lion Miter Trimmer.
After the miter was cut, I would use the miter trimmer to shave off a slice of wood at the miter. That slice was so think that if you held it up to the light you could see through it.
I really could not tell you how accurate the Stanley was, because I always trimmed after cutting the miter. But is was supremely easy to use, mostly because of the length of the saw (probably around 20”) and the bearings that guided the saw.
I continued to use that professionally until I bought a dedicated miter (90 degrees only) sliding table saw.
Lion is out of business, undoubtedly because the cheap knock-offs were of good quality (though the replaceable blades are not to the same standard as Lion’s).
https://www.infinitytools.com/blog/2021/02/11/the-precision-miter-trimmer-saves-the-day/
Stanley is marketing a similar design now (very cheap). I recall spending a little over $200.00 in the mid1970s equivalent to $1,140.00 dollars in 2022. So clearly not of the same quality.