The latches that allow you to pump fuel hands-free usually have 2 settings and even the highest setting is not 100%. It seems like 80-90% of the max pump rate imo. So you’re right that it does pump slightly slower when using the hands-free latch.

The fuel nozzle is a completely mechanical implement - there’s nothing electronic about it, and the pump has no idea whether you are manipulating the trigger or using the hold-open.

Because it’s mechanical, however, the way the hold-open is designed needs to allow for further actuation of the trigger mechanism to free up the hold-open lever when your tank is full. Because of this, the highest setting on the hold-open is less than the full actuation of the trigger mechanism.

It shouldn’t. The latch just secures the handle in place so you don’t have to hold it down. As long as the latch presses the handle down as far as it can go there should be no difference.

The latch is mechanical for most pumps so probably no.

Now, if you want a definitive answer you need to test this. Pump with or without the latch and with a timer. Compare!

I’ve seen those same latches all across the US and I can certify that the gas usually flows slower when latched.

But it’s not because it’s designed to flow slower, but that the latch holds the tube open in a more closed position than when your hand is squeezing the handle.

They don’t pump slower. Here’s a video explaining how the handle works: https://youtu.be/fT2KhJ8W-Kg

There is no way that the pump can detect the use of the latch and slow down (and why should it anyway).

Here in Texas most of the gas pumps have two or three notches for the latch to go in, so the speed is adjustable. It seems to me like the highest setting is usually pretty close to just holding down the handle at full blast, minus a little bit of play in order to get the latch into and out of the notch.