Executive compensation is a drop in the bucket compared to the total salaries for all the rank-and-file employees.
According to your article the average hourly labor cost at GM is $60. Assuming 2,000 hours per year, that is $120,000 per employee. For 92,000 U.S. employees [0], the total is about $11,000,000,000.
Another way to look at it: If you distributed the CEO's compensation ($30,000,000) among GM's U.S. employees (92,000 [0]), you'd give each of them about $326.