Yep, piebald is a simple recessive trait. There are lots of other simple recessives out there, such as albinism, leucism, clown (ball pythons), and blue eyes (humans). Without getting needlessly complicated, animals that have repeated sequences (called tandem repeats in genetics, for example: ACACACAC) in their genes tend to have the most variability in skin/coat color, body size, etc. Basically, these tandem repeats give an animal's genome a great deal of flexibility, allowing them to adapt more readily (e.g. in fewer generations) to changing environmental conditions.
Most domesticated animals (dogs, cows, cats, rats, etc.) have lots of these repeats, and that's why we've been able to generate so many different 'morphs' or 'breeds' of these animals. Other animals that don't have as many of these repeats tend not to be as genetically malleable, and so it's harder to locate animals that have odd appearances (such as many species of reptiles and amphibians). For example, I doubt we'll ever see as many recessive bearded dragon morphs as we do recessive leopard gecko morphs, even with some of the genetic discoveries that have happened lately.
For an even more basic genetics lesson, every animal has two copies of a single gene. One copy is inherited from each parent. With recessives, both copies of a gene must be present for that recessive trait to be expressed. If you only have one copy, the 'stronger' normal gene will overpower the recessive gene, and you'll still have a normal looking animal. The reason albinos, leucistics, etc. are rare in the wild is because it would take two heterozygous parents (e.g. each parent has one copy of the gene) to produce a morph offspring, but you'd only have a 25% chance of actually getting a morph in a het to het breeding. So, if you're a deer, and you only have two fawns a year, you'd only have a 1 out of 4 chance to get a piebald/albino/leucistic baby. And even if you do have one of those babies, those recessive traits tend to make the babies stick out more to predators (think of an albino fawn and how obvious that would be to a coyote while it's hiding in green grass), so they rarely survive to adulthood to breed more odd looking animals.
