As others pointed out, that was likely intentional. Apple designed this safety mechanism into the laptop, so they would not have to deal with such warranty claims.
Also the temperature change is not a problem while the laptop is non-operating. The alternative therefore is to wait for 10-15 min before turning it on.
This is not entirely accurate. Electronic devices are fogging up just like my glasses everytime I come inside. This is known to trip the water sensitive stickers used to deny warranty, even if the problem is obviously unrelated. Those are triggered regardless of if the device is powered on or off. To me this is strong evidence that electronic devices are not tested properly for our climate.
That moisture indicators are used as a way to weasel out of warranty claims is indeed common. But that was not what I was referring to.
What I mean with having fewer warranty claims is that the Macbook doesn't break in the first place. Condensing water is not a problem while the device is powered off, and will evaporate once it reaches room temperature.
Also the temperature change is not a problem while the laptop is non-operating. The alternative therefore is to wait for 10-15 min before turning it on.