Unless you're playing a map meant to have more Civs, it should be manageable. Again, a lot of it is under player control. Are barbs raging? Playing too few civs on a large map? (some people like that)
That said my experience with barbs plundering my trade routes gave me a nice kick in the butt to 'project' force. It certainly makes that early trireme worthwhile.
Also, you don't need to have a unit spaced evenly to stop pillaging. You just need a unit nearby that can respond to a threat. At worst it gets pillaged once and the threat is known and you can eventually knock out the offending camp, but yea, projecting power is required.
Also early routes are quite limited by distance; unlikely to have cargo ships and the harbour distance boost, caravansaries may not yet be built so it's going to be by land to a nearby CS.
If you can't protect that, then there are other issues.
Again, some people play custom map types where barbs are everywhere even far into the game. I can't speak to that obviously as it's not the standard game.