Why is the international date line not...

If the date line were at 0 degrees longitude, Madrid and Berlin would be on different dates, and the eastern suburbs of London would have a different date than downtown. Any meridian could have been selected as the date line if agreed on, but the one chosen, 180 degrees longitude, is suitable because it runs almost exclusively over water. At the few points where it interferes with land, the date line was pushed a bit back and forth so as not to split one country into two areas with different dates.