SA won't tell you how the work procedure or step by step stuff because that one they also refer to manual and is consider company's private information.

As you asked, WHAT IF something happens accidentally during the repair. like your example airbag deploy. Now the technician will need to inofmr to his superior eg. the lead technician (supervisor la). Then need to ask why the incident happen (most probably due to technician error, skip procedure loh..no disconnect battery) then supervisor need to inform SA, SA need to inform customer. Then customer sure hoo haa hoo haa very angry one...who won't be..then SA need to nego with customer how to solve the problem because customer sure angry mah car need to stay in workshop wait for new steering. Then SA need to inform the boss and order new parts but the technician will need to foot the bill la....because he didn't follow procedure mah....

There are occasions where a technician do something wrong and not inform the supervisor also geh...and hope the customer won't find out...example dismantle dashboard...I can tell you 70% chances you will lose 1 or 2 screws that hold the dash after they fix back (some 3 to 4 screws also have)...or a few clips missing or they scratch something, or break a few clips....this things are hard to avoid unless owner stand there from start to finish the work....because all these after fix back cannot see mah....

Sometimes the supervisor also kao tim kao tim with the technicians geh....example they break something then tell customer "when we open your bonnet we saw this broken" (actually they broke themselves.) You know loh how many Malaysian driver actually check their engine every week or take a video or picture of the engine bay before sending in to the workshop. By that time, you want to say it's not broken, but no evidence to show, how to argue. That's why I have a  habit of taking pictures of the engine areas, the sensors or record a video with all the engine sensors or stuff that might come into contact with the technician when he do repair job so if he really so bad luck damage anything I still can show him picture "see, I took this before send in to repair" But such thing rarely happens as it depends on the technician that is working on your car..whether he's playing playing when doing job or serious....

Still, the technician that is doing their job is the key....if they have the mindset of responsibility then everyone won't be so paranoid.