Is this a problem with the specific mechanical calipers used on Lectric bikes. I have Tektro mechanical calipers on a relatively fast ebike and go down steep hills routinely and I have had no problems.
The problem as far as I know it, is that cables stretch much faster than the pads wear out and need constant adjustment.
Cheap ebikes tend to use cheap brake cables.
I read that there are better quality brake cables that use stainless steel wire with very little stretch.
Brake cable wires can also bind up inside the sheath with all kinds of friction that has to be overcome with a stronger pull on the brake levers.
I can lock up my front wheel on pavement with one finger on my 100 pound ebike.
One thing I do worry about with hydraulic brakes is if a hose gets cut, nicked,or crimped. The hoses don't seem to be armored in any way. Could somebody disable your hydraulic brakes with a pocket knife?
Yes, that's true.
The ridged plastic hydraulic brake lines can be cut/nicked more easily than steel brake cables, but you do have front and rear brakes, and damaging both brake lines at the same time is unlikely.
Sabotage is different, but you should notice that really quickly when you pull the brake levers and the lever hits the handlebar.
I always grab the brakes when I get on and off my bike, so I should notice any issues.
I do notice that my rear brake, with it's much longer brake line has a much spongier feel to it than the front brake.
My brake line moves when I squeeze the rear brake lever when I have the brake line clips removed.
The line is flexing, but I can still lock up the rear wheel with one finger without the lever hitting the handlebar.