This is again presupposing a design or maintenance instruction flaw.

There's a thousand of these aircraft, and they've each been through multiple D checks where all of this is completely disassembled and put back together; then there's other maintenance that causes disassembly and reassembly, too. In tens of thousands of opportunities, it looks like one time a wheel assembly was not fastened adequately.

It's possible procedures can be improved to make this even less likely. But maybe not: people make mistakes. Sometimes someone signs the line saying that something was torqued and didn't realize they had torqued something different.