More often than not, retail workers behind the counter in smaller stores are required (by their employer) to greet customers as they enter. It’s a tactic to reduce theft. However, employees hate doing it. Most customers understand its a mandatory part of their routine and hate it, or at the least are indifferent. It’s an insincere greeting that nobody cares for, its just something employees have to do, or they get reprimanded.

Your customer encounter is not normal American behavior. Expecting to be greeted is a sign of entitlement (which is the likely case, due to asking for your manager) or possibly mental health.