A sacrifice bunt in baseball doesn't seem to count against on base percentage is a sacrifice bunt therefore not considered to be a plate appearance?

Answer 1

It is in fact the only stat that may not be included as a plate appearance. While unique it is also confusing because it is up to the discretion of the scorekeepers as to whether or not the batter was bunting in an attempt to make it on base, or if they were indeed bunting to progress other players. If the scorekeeper rules that the player was in fact trying to progress other players with a disregard for whether or not they themselves make first base, then indeed it does not count as a plate appearance (unlike a sacrifice fly which regardless of the intention will always count as a plate appearance, but not an at bat.)