It's probably working as designed. Most people in ESTA countries qualify. The list of country visits that disqualifies you is North Korea, Iran, Iraq, Libya, Somalia, Sudan, Syria, and Yemen, all places where the US is hostile to the government or a major indigenous rebel/terrorist organization. The US government won't ban you outright for going there, but they're happy to deprioritize you.

Compare with China, a non-ESTA country that makes the US a lot of money. The wait time for a visa appointment in Beijing is two days.