Comment by tacitusarc

There is no amount of maintenance that can avoid all mechanical issues. Take bird strikes, for example.

Regarding "carry insurance": margins in the airline business are notoriously slim. They compete very heavily on cost, because the service they provide is a commodity (or close to it). Most airlines will probably not willingly add any extra costs that they don't have to, because that would put them at a disadvantage relative to their competitors.

For those passengers who are willing to pay extra to be reimbursed for delays or other inconveniences, there may be travel insurance that can provide that.