Outsourcing car work to company's

I am building/restomodding a car, and why is it till now literally 1 company actually did a good job regarding the service I requested.

1. I brought 2 hubs and bearings to a shop to get pressed
   Find out that they didn't even press either one far enough in as the retaining ring was just resting on the outer edge of the hub (find this out as sh*t didn't align at all and made me wonder why)
2. Brought some rubbers that needed pressing in and some stuff to weld to a shop
   Put to much heat into a rear lower control arm so now the circle is a oval where 1 of the rubber supposed to go in so that didn't go in and he messed that up, then he also messed up a rubber to goes into the knuckle, later found out he put to much welding material inside the diff so I needed to trim that to to make the cv axle fit

How come people over estimate their skill and cannot say they never did that before so they are not sure if they can get this done as this

1. saves me time
2. saves them time
3. saves them money (reimburse the broken stuff)

As to also when contacting them their solution is to ''stop by'', yeah like I am going to drive 1 hour single trip to get shit fixed while this was their fault in the first place