Why is Vtyp less than Vmin on a CMOS chip
This question is all about the required input levels into a logic device

The minimum value for \$V_{IH}\$ is the guaranteed value for a "1". In other words, if you equal or exceed this level the input circuit will definitely recognize it as a logical 1. Typically it might work a bit lower than this.

As for \$V_{IL}\$, the maximum value is that input level that would be definitely recognized as a logical zero. Typically this may be a tad higher.

If you look at this picture it might help: -



It describes inputs and outputs for a typical 5V logic scenario. Note how \$V_{OH}\$ (for an outputting device) is always bigger than \$V_{IH}\$ for a receiving device - this guarantees correct and unambiguous operation. This scenario would not be "spoiled" if \$V_{IL}\$ was a little bit bigger and \$V_{IH}\$ were a little bit smaller and, of course, this is where the typical values come in.