In some fields of engineering PE is pretty nonexistent. Some people come from other degrees (like math, physics) and call themselves engineer without difficulty. But engineering fields require a much more narrow and deep set of skills. generally the key classes to learn those skills come at the end of three or four years of prerequisite classes, so it's a pretty high barrier to starting without doing the degree.

In programming you can learn your way to advanced skills while getting paid. Once you know roughly one class worth of basics there's valuable contributions you can make, at least if you are decent at figuring things out on a computer.