Don,
You should have mentioned to your mechanic that the condensor read 5k ohms instead of infinity. I have taken the same 40 mile ride as I did before I fixed it with no failure. On the previous ride it failed 5 times.
I don't know about lawn mowers but they may suffer from the same environmental conditions as cars, or maybe they are more cheaply made, or maybe it was really the plug wire that failed as they are usually monolithic.
Ron