I heard from an engineer (where’s TDR when you need him?) that you are less likely to get bits of birds going down the engine core at high thrust settings, e.g. takeoff, as the remains get flung outwards through the bypass duct. I have had birdstrikes at night and only found out about them when the sun came up and you could see the mess.
Long story short, modern engines are tested with bird carcasses for certification but with the Korean accident it looks like they flew through a large flock which damaged the airframe as well as the engines, which is bad luck. As others have said, you do get warnings but they are often 24/7/365 “bird activity near the airport” which there is not a lot you can do about. Birdstrikes are fairly common, damage, especially severe damage, quite rare.