That's probably true, but the potential for a severe, un-recoverable issue is about as high. An aircraft is composed of hundreds of individually tracked components with associated information about how old the component is, how much it has flown, etc. Most of these parts have a mandatory expiration date at which point it is swapped out or sent for repair. A failure in the system which tracks all this data (which is what I work on) isn't quite as directly dangerous as, say, a bug in the on-board navigational software. But you can still end up flying around with an engine way past its intended expiration date far too easily.

The actual on-board software of an aircraft is definitely given a lot of attention as far as testing is concerned, but unfortunately more indirect systems, such as maintenance tracking software, is treated pretty much the same as any other piece of software; which puts it down to the company that made it to judge how much testing they perform.

In my company, the management puts a higher priority on putting all available hands on rolling out new functionality than fixing bugs, in order to try and win new contracts from potential customers. Or at least that's their excuse, in my opinion there is no such thing as a low priority bug, no matter what industry you're in.