Yes, thats why I think it's a huge problem for the industry. How the heck is it possible that so many developers with bachelor and master degrees which otherwise do a reasonable job don't even know that they have a dangerous knowledge gap there???

through that:

> in the worst case customers seing other customers data because of the wrong transaction levels.

should not happen even with wrong transaction levels, that indicates some additional serious design problems IMHO, likely related to premature optimizations