Let's have a look at process control applications:

Switches are used to tell the process control that a certain parameter has reached a certain threshold. The switch is either opened or closed. To fabricate a digital signal from it, we need to make the switch part of a voltage divider. So, we could use a pull-up resistor and the switch to switch to signal ground (GND) or we could use a pull-down resistor and the switch to switch to a supply voltage.

What is better? The switching to GND, or the switching to a supply voltage?
Of course, the switching to GND, because the GND wiring is nearly always more massive and lower impedant than any other signal routing and will show lower voltage drops and by this lower noise. Or by other words, switching to GND will nearly always provide the highest noise margin.

When driving outputs, switching to GND is also advantageous: In a process control application with devices being powered by different supply voltages, the NPN open collector output, like it's used in the famous 74TTL-logic family, is ideal. Equally what (positive) supply voltage is used in the device to be controlled, the driving NPN open collector output will always properly transmit the low and the high state, by either tearing down the input to GND against the individual internal pull-up resistor or by turning-off the NPN transistor and leaving the individual pull-up resistor to make the high level. Or by other words, the open collector can turn-on a load without "knowing" about the supply voltage of this load. There's no path needed to this supply voltage, like when a PNP would be used to turn-on the load.

Switching to GND is natural, just because 0V is the unique potential in any electrical system, is represented by the most massive and lowest impedant electrical connections and by this nearly automatically guarantees the highest noise margin.

Also, when several different supply voltages are used in a process control application, there will be as many different high levels as supply voltages are used, but only one zero potential, because 0V is unique. So, switching to GND, via a NPN open collector output, for instance, is natural.

What this has to do with "negative logic"? Nothing...

Kai