It's a true statement within limits ;-) It starts getting fussy when you have 100' of thin tubing.
There are other things to consider like how well the tubing is wetting, air bubbles, air locks, and even microbubbles you can't see. Dye so old farts like us can see the water level. Detergent to minimize wetting/meniscus parallax problems etc.
You have to set it up carefully before you can trust it. It's not quite so portable. And sometimes you get wet ;-)
Decent tubing for a water level may end up costing more than an "adequate" laser level.
So they may not even be cheaper. But they _will_ go around corners ;-)
There are benefits to both.