Figure 1 - Clogged drain
With that being said, the following common home repairs could be done, and probably have been done in the past, by your grandmother!
Clogged drains: You don't need to call a plumber every time your drain is clogged. Just get yourself a drain snake (they sell them at Wal-Mart and just about any local hardware store). Run that thing down your drain and Voila, your drain is no longer clogged. If that doesn't work, or you just don't want to buy a drain snake (though they are inexpensive), grab yourself some drain cleaner. If you have a septic, just make sure whatever brand you get is septic safe.
Flooded basement: If you have sump pumps and your basement floods, your sump pumps are either clogged up or dead. Just put on some waders, or daisy dukes, and reach in there to troubleshoot. That water won't hurt you. You bathe in it regularly (I hope). Be sure to cut off the power to the sump, unplug it if it's not hard-wired, then feel around below it to see if it's clogged. If so, unclog it and you're good to go. If the sump just isn't working, make sure it's getting power. If it is you probably need a new one. They aren't expensive and you can follow the directions provided by the manufacturer for installation. It's easy to do.
Figure 2 - Dishwasher replacement
Figure 3 - Flooded basement
Dishwasher replacement: Replacing a dishwasher is easy. Yes, your grandmother really could do it. It's as easy as removing a few screws and loosening a few clamps. Just turn off the water, disconnect the drain pipe, water line and power supply, and pull the old one out. Now reconnect all of those things on the new one. Once it's in place, adjust the four corners so the height is just right. It's quick and easy and anyone can figure it out if they just try. No need to pay someone several hundred dollars to do something you can do in about 20 minutes.
I've named only a few of the many easy household repairs that could be done by just about any able-bodied person. What it really comes down to is the willingness to figure things out. Never believe that you can only do those things you specialize in. Many things in your home, and in life, can be done by the average person, if they're only willing to put a little time and effort into figuring them out.