Short answer: Because your family will miss you if you don't miss that gas, water or electric line!
Now for the long answer:
Our land has become very busy with utilities being installed under our feet and with the many new no dig ways to install utilities you may never know they where ever there! You go to work and so do utility companies installing gas, water, electric lines without even stepping onto your property or even digging on your property, and when done, Clean up and leave before you come home. This happens a thousand times a day !
Many codes state a minimum of 3 feet deep should be all utilities, BUT things happen and utility lines can drift up closer to the surface, and if you go and start that minor to a major project without calling for a utility mark out, YOU can get very hurt to even losing your life! Do you want to do that to your family?
Always call for a mark out and it it is past your meter, call us to locate your utility lines before you dig and always dig safe !