Is this datasheet wrong?
The DTA124 is a PNP transistor originally made by Rohm, and Rohm's datasheet is consistent.

Taiwan Semiconductor intends its DTA124 to be clone of that, so it must be a PNP, too. There are lots of similar DTA/DTC datasheets for all the resistor combinations, so it is somewhat understandable (but not excusable) that these copy/paste errors can slip through QC (especially if you have to cut costs to be profitable at cloning).



As for the ground: Taiwan Semiconductor copied some NPN circuit image, and left out the complete explanation of the PNP signals:



Here, the ground is the most positive part of the circuit. And since the emitter is the fixed voltage against which the other voltage levels are measured, it is technically correct to call it "ground".