Edit: This was in fact visible - there is at least one video out there from much further from the likely impact in Cape Cod Bay
Afaik it's not unusual for truck-sized objects to woosh past Earth, detected only after their pass. Or just days before. Weeks if lucky. Not a timespan in which one could mount a divert-mission.
Possibly this applies to bigger objects too? Some objects have a very dark surface & are very hard to detect in any case.
Why stop at 200 years? It's also 300 years and 400 years, or 4 billion years :P