Voltage differentials in the earth that exceed 1500V will occur even without a lightning strike, and the greatest danger is when the ground is dry. Even something as simple as a strong wind blowing on a tree can charge things up significantly...
How interesting! How do old-fashioned wired telephones and cable TV deal with this problem?
The cable TV shield is grounded where it enters the house. The POTS lines aren't grounded (they're differential, like 1000base-T), but the telephone company installs some sort of protection device in the exterior box that allows sparks to jump across to the local ground if the voltage differential gets too high.
It’s so frustrating the amount of over generalization, anecdata that’s actually dangerous, and/or outright misinformation in this thread. Thank you for being one of the folks with spot on accurate info!