Hi,
This PNP, on the first page, shows the emitter as being ground...in that case, it would never be able to turn ON, unless the base went negative.
Why have they done this?
Logic transistors are mostly used in CE configuration (read: common = ground), that's what the datasheet assumes. No assumptions about supply voltage polarity and positive or negative logic.
Exactly what I was going to say. Noobs wrote the datasheet.
Or the person who wrote the datasheet drives (on the wrong side of the road) a classic old English car that has its battery positive as the ground.