I'm a new parent of a 18 month old so schooling is a bit off for her.
I look at it kind of like Social Security. I am sure a better solution exists but I feel like enough of my money has been directed at this cause without getting a benefit that I want to see a return on my investment now that I can.
I certainly understand what you are saying. BTW, you will be shocked at what your 18 month old can learn already. Do me a favor. Just start with the letter "O" and point it out just like you do a bird or a dog or whatever. When he's got that one down, go on to a "T" or something totally different. Make a game out of finding the letters in the newspaper (headline print size). Everyone will think your kid is a genius and it's really easy to have them recognizing the whole alphabet even this early. If he's not talking (mine wasn't much) just point. They love it.
Then go on to letter sounds. Then buy a good phonics reading program and voila! He's well on his way to a great education pre-K.