I’ve got a single similar (yet not as potentially deadly) Canadian Tire story about the mechanic winging it and failing to inform.

Single because it’s the one and only time I’ve taken my car to a CT for servicing.

I just haven’t trusted since then that CT has the necessary processes and procedures in place to prevent stuff like this, instead leaving things up to the individual mechanic who is under pressure to just get the job done, and who feels anonymous under the CT banner.