But South Korean are eligible for ESTA program. IIRC, US embassies in eligible countries are usually very picky about issuing B-1 visas. They assume ESTA works

But South Korean are eligible for ESTA program. IIRC, US embassies in eligible countries are usually very picky about issuing B-1 visas. They assume ESTA works in most cases, so you need a strong reason to apply for B-1.