1stly, is it a blob, or an X?
2ndly, is there a pilon with either a light out, a transformer or a cable nest in it?
3rdly, have you noticed any cable works down the road?
4thly, is your neighbour Dominican? If so, you do know they know everything and if they don't they will casually invent for your benefit.
The only time I've seen red crosses on pilons or roadway, walls, pathway (whatever) is when they expect to be relaying something, are marking existing boundaries with a transit station (say boundaries of a property etc.) The transit stations are also used by surveyors to see if there has been any ground movement by continuously making measurements from two points, if the measurement changes then they can see how much ground movement has occurred over 'such and such' a period. Maybe your gate or another point of significance has moved and they are investigating by how much.
But I'll bet the only 'Red Cross' gang in Hispanola is in Haiti on humanitarian duties, not painting people's posts.