I chalk it up to a bunch of nervous ninnies and self proclaimed risk assessment experts.
Its easy tagging people who encountered issues as "nervous ninnies". The fun part begins when "macho photog" hits a bump.
I've already given my opinion on the issue. While it is of course "self proclaimed" as all opinions are, it is backed up by a bit more than 30.000 correctly documented support cases since 2001 and probably something like 100.000 so-so (in terms of information accuracy) other cases.
You bring up another good point. Use your gear for a while before taking it on a paid job. Test, retest, put it through the wringer before using it for important work.
Cards do fail. It's why the card companies have RMA services in place. And I'd like to see some reliable statistics on the percentage of cards that fail. I suspect that number is very low, much lower than cards that get lost, misplaced, accidently written over, etc.
The current rate of true hardware failures is quite low indeed, the positive trend started around 2006.
And I further when these failures take place. Anyone familiar with electronics know most electronics that fail, fail within the first few days/weeks of use. It's been my experience that once a card works fine for a month or so, you can almost consider it bullet proof.
This is, in general, a good rule of thumb. However, there are several nuances when it comes to card. The media itself has a limited life expectancy that is very reachable, especially with poor wear leveling algorithms (that's in practice similar to light bulbs, except that some clever load spreading is active in the background). The controller is essentially a small computer with its own firmware and the field is (was) evolving quickly. When you have a device that's not working with a new computer and/or OS you either upgrade its firmware or driver and that's it. When a card encounters a similar issue it is, for all practical purposes, dead for the user. Lexar has on several occasions updated the firmware of cards and that firmware upgrade restored access to the customer data either by making the interface more compatible or by improving defect management and bypassing the troubled area). Last but not least, the interfaces between the card components are relatively thin and subject to more mechanical stress than, say, in the midst of a rigid phone.
In contrast.. camera equipment. Their electronic components are in the same class. But their mechanical components fail more are they wear, get dirty, don't get maintained (cleaned and lubed), jolted, etc..