Segmental retaining walls, like unilock or any of the many, weep between the blocks since there is no mortar. You should have perforated pipe running at the bottom of the cut or fill to carry away water so that it never builds up in the first place.

The wall should have well draining gravel behind it from top to bottom. Then there is no water build up, it just goes down to the perf pipe. The perf pipe needs to be able to carry the water to daylight, a drywell, or a leaching trench away from the wall.

There is no reason to have a 4" opening above grade on a unilock wall that I know of. This is something that would be done with a poured wall or timber wall. My guess is that the guy who said you needed the weep holes is older or at least old school and not up to speed on segmental wall construction techniques that have been well developed over the last 15 years or more.

Thanks for the quick reply! That was my impression, and I think I have him convinced that all he has to do is run the sock pipe (which he was doing anyway) to the ends of the wall and have plenty of gravel around it. I will probably just drain it at the ends, since the height slopes downward on each end of the wall.

It just sounded really ugly to have those drain holes in the front and I would worry about cracks from drilling that might weaken the blocks. I have had other walls built at my prior home and know that the wall will be wet following rain, but I just wanted to be sure I wasn't missing something here.