In watching the local news and weather the traffic report lady

[Beachnutt]

always says "right or left Hand lane", what does the Hand have to do with it ?
Right lane or Left lane
Right side, Left side

[Marthe48]

1. Probably just a regional idiom carry-over

But the way people drive around here, maybe the extra descriptive helps them figure out what lane they're in :/

[Tetrachloride]

2. Linguistic redundancy increases automatic error correction.

[HariSeldon]

3. "Right" is sometimes synonymous with "correct"

"Right lane" can mean "right hand lane" or "correct lane," and the context to determine may not be immediately present. Additionally, "left" can mean "departed" or "abandoned," though "left lane" is generally clear.

[Effete Snob]

6. First thing I learned today

https://jakubmarian.com/right-side-vs-right-hand-side-in-english/

The problem with “right side” and “left side” is their ambiguity. For example, when someone tells you:

Write your name on the right side at the top of the page, please.

it is not clear whether you are supposed to write your name on the correct side of the sheet of paper or in the upper right corner of the side you are looking at. By using “right-hand side” and “correct side” instead of “right side”, you can make your statements unambiguous.

“Left side” is similarly ambiguous (although its ambiguity is much less likely to cause any misunderstanding) because “left” can also be the past participle of “leave”, so “left side” could be understood as “abandoned side”.

[MiHale]

4. Oh I get it now...

That’s why I have a “R” on my rightin’ hand and a “L” on my leftover hand.

Thanks!

[Effete Snob]

5. My wife does that

It has puzzled me for years why the "hand" is in there, and I've chalked it up to a regionalism.

[Chakaconcarne]

8. I try and stay away from the far right lanes....

Left lanes suit me better... Less obstruction and nonsense...

It always amazes me the people in the far right lane continue to stay in that lane, while the rest of us leave them behind....Not sure what they're so afraid of.