Actually, I've repainted pools numerous times, successfully.

But, I've ONLY used Kelly Technical's epoxy, and I've been very careful with the application. Applying epoxy successfully is difficult in that there's little room to 'fudge': you do it right, or it fails. It's not highly skilled, but it is picky.

Most of the paint jobs I've seen other contractors do have been failures.

Delamination, like you describe is usually a bond failure. Two common causes are dirt / dust on the primer or allowing the primer to cure too long.