lmao... I was thinking the same thing (─.─||）
They don't need to. If he has A, he can accept from O and A blood types. If he has B, he can accept from O and B blood types. Lastly, if he has the rare-ish blood type AB, he can accept from O, A, and B but he can only donate blood to someone who also has blood type AB. If he has O though, yeah everyone also has to have blood type O to donate to him in that case.
Wow! Are you a doctor? I didn't know that. (☉｡☉)!
Lol no it's pretty basic biology stuff ^^;
One thing I forgot to mention though, is that O is the most common blood type that there is so even if he is blood type O (and therefore can only accept blood from O donors) there's still a higher chance that others are also blood type O than any other type. So it's all to say that it's not that unrealistic that he can receive blood from so many people.
there are only 4 (common) blood types. unless hes got weird ass blood type like AB- or smth, and being that O is the most common blood type, and considering the amount of people there, itd be more surprising if he couldnt get a matching blood type.
Quite convenient how everyone who donated blood had the same blood type as the guy who needed it… seems a bit too convenient…