I guess I need to comment on my own comment. I have made well over 100 carved wood signs using nothing more than hand carving tools and hand painted. I have also made about the same amount using a plunge router by hand, finishing with chisels and painted by hand. Most of these were painted with oil based slow drying primers and bulletin enamel. About 15 years ago I began using high quality latex paints. In my climate, I found the signs would last about 5 years, then slowly the paint would start to crack and fail, requiring maintenance. If left alone, once the paint began to fail, the wood would begin to rot and after a few years it was all over (unless you were a fan of really "rustic" looking signs). About twenty years ago I experimented with the new HDU products that became available, with good results, but by that time I was deep into running a profitable electric sign shop and had no time for hand carving. As 3-axis routers became available, I started buying dimensional HDU signs from wholesale providers, and found with proper priming and painting with acrylic urethane, these signs would look new for well over 10 years. I have some that are twenty years old that still look great.
For a production sign shop with a lot of overhead and expenses, it hardly makes sense to hand-carve and hand-paint signs when high quality results can be obtained at a fraction of the production cost using routers and commercial spray coatings. It takes years to learn how to carve, brush letter, gold leaf, and properly hand-finish a sign, and few people are willing to learn how to do it or spend resources training new employees the art and craft.
On the other hand, smaller, craft-based shops can, and do, continue to make beautiful hand-made signs. Most of these artists have spent years learning how to do this, on their own time, with pride of their craftsmanship and the mastery of the art being the primary motivator. Sure, you can make more money jobbing these out, but the satisfaction of working with your hands and the customer's satisfaction of knowing they just received something hand-crafted by an artist has its own set of rewards.