Because amphibians have very soft body integuments, their body cannot withstand the constant burning of the sun. Also, amphibians breed in the aquatic environment, and in the desert we are unlikely to find even a puddle. Reptiles have horny scales that protect their skin from drying out and they do not need an aquatic breeding environment, because they are oviparous.
One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.