Why do they do it?

I was asked to investigate a ABS warning lamp indicating a fault. The scan tool lead me to the offside rear ABS braking circuit. I looked at the sensor and wiring and it looked in good condition. The boss said there is no live supply showing?

So he had scanned it before me. 

My investigation concluded that the car, a Nissan TIIDA was using magnetic sensors and not Hall effect. 

Having no technical data on this car ABS system I then compared ohm readings from each rear ABS sensor. Years ago I'd of said if I'd of seen readings around the 1500 ohms range I'd of then said it is possible that the sensor will work but ideally a scope trace would be better!

I used the live data on the scanner and only the offside rear ABS did not create a voltage signal.

My boss asked me to change the ABS sensor but I said I'd not convinced the sensor is at fault here?

I did as I was told and started to remove the old ABS sensor when the bearing hub was excessively corroded and broke up when I put a 1/4 drive 10 mm socket on the nut and started to turn it. 

I ended up removing the whole brake assembly to fit the new hub. After removal of the brake disc I saw that the park brake shoes linings were at least 50% missing from each shoe. We ordered the new shoes.

While dismantling the brakes I asked who fitted the new brake pads to the same axle I'm working on. My colleague I'm told. I commented on the disc condition and asked why on service standards the discs were left on in a corroded condition! I didn't get much of a reply.

Today after fitting the new bearing hub yesterday and fixing the ABS fault, which was caused by the ABS ring inside the bearing hub being excessively covered in metal particles, thus stopping the sensor reading correctly. I started to dismantle the nearside rear brake assembly. I saw the new brake pads fitted and the disc did not look that bad on that side so I didn't question anything. When I used a spanner to loosen the brake caliper lower pinch bolt to secure the caliper to the brake pads carrier, I heard a cracking sound. I then looked at the brake assembly and could see a mig spot weld on the brake caliper pinch bolt.

Who then with a sound mind would put new brake pads in a braking system, and then spot weld a sheared pinch bolt to hold the brake assembly in situ and send the car out for service to the public!!!

Today I had to travel a good distance to a local Nissan breakers to buy secondhand brake pad carrier and pinch bolts. No way was I going to put my head in the chopper. That was just a recipe for a manslaughter case for sure!