Something is not adding up wrote:
all it would take for there to be a mass outbreak would be ONE person with it to travel there and infect a couple people. That doesn't seem to be happening, so what gives?
That's what surveillance/detection and contact tracing and quarantining and isolation is for.
Countries that are doing it the best are surveilling everyone coming into the country. As an example, in Taiwan, that means testing all arrivals at the airport, giving them a 14 day supply of masks, taking their contact information, asking them to isolate in their hotel room for a 14 days, following up with them when as soon as they get to the hotel to make sure they aren't breaking quarantine, calling to check up on them daily as they quarantine, monitor them with a contact tracing app. There are large fines for breaking quarantine. The little details might have changed somewhere along the way, but you get the idea. They don't let things slip through.
Contact tracing: In the US, locally I've heard of resistance to contact tracers from many who test positive. They don't pick up their phones, perhaps feeling shame, even though there are no penalties and it's a public service to warn other people they have potentially come in contact with. Vietnam, as a top example, does a thorough, 3 degrees of contact tracing. F0 is the infected person. They check on F1 (F0's contacts), F2 (F1's contacts), and F3 (F2's contacts). And they know there is a very limited amount of time to do this contact tracing before a newly infected person starts shedding virus (2 days before symptoms), so they do this all within 3 days. If a contact tests positive, they go to isolation at a hospital, even if they have no symptoms so they aren't spreading it around. If a contact tests negative, they quarantine at a government shelter for 14 days. You put them up in the shelters to solve the problem of covidiots. The government pays for all this testing and isolation and quarantining, because there is health care for all and no one falls through the cracks.
Notice that the contact tracing in Vietnam is all based on contacts, not symptoms, because if you go by symptoms, you have people walking around shedding virus and spreading virus before they feel sick or they never feel sick but still spread the virus.
When there happens to be that one community spread case that they can't contact trace, they lock down the targeted area, which might be 100 people or 10,000 people. Better than the whole country, and for a lot shorter period.
Of course other measures are in place like travel restrictions, consistent messaging (not masks don't work, masks work) and encouragement from authorities, shut down of misinformation, etc.