[arijun]

Why wouldn't you always leave the car in reverse? It has a lower gear ratio than 1st.

[londons_explore]

Reverse typically has a higher gear ratio than first. Normally between 1st and 2nd in terms of ratio.

[inferiorhuman]

Why wouldn't you always leave the car in reverse?

If I'm worried about the car rolling, I don't particularly want it turning the engine backwards.

In terms of ratios I don't give it much thought. On pretty much every car I've driven first gear is shorter than reverse (typically first is > 4:1 vs reverse at < 4:1).

[eknkc]

Probably has a higher chance to mess up the transmission in case of a load (small impact) due to that lower gear ratio.