Your math is wrong, too. When you are losing 6-0, 6-0 in a best of three set match, you are only facing closer to 24 first serves.
You trying to equate baseball batters with tennis receivers tells us tennis is not your thing. A tennis serve has more dimensions than a baseball pitch, and the receiver needs to cover a much larger distance.
Some of you are making it sound like one can easily return good serves with practice. But know that on ATP tour, 38% of first serves do no come back - they are aces or unreturned serves.
If the pros cannot return more than a third of the serves they receive, what chance do mere mortals have?