These lines were mostly tagged with power=pole, not with power=tower. The latter is usual with high-tension lines and I therefore got warnings by OSMI.
Mid-tension lines (<50kV) are used for distribution, high-tension lines (>100kV) for long distance exchange.
The 60kV lines in Algarve are mostly used for collecting wind park energy and are somehow in between.
By having a closer look the tagging of these lines in this region is very inconsistent: It is a mix of line/minor_line and with tower/pole although of same size and pole/tower distance. In high resolution images it looks more like single poles than (lattice) towers.
Anyway, I have no objections against power=line at 60kV, but this should be done consistently.