Why aren't one-off costs enough? There is *no* re-occuring costs with a
cable hanging on the ceiling.
See previous post wrt insurance,utilities,rent and manpower costs.
D-Rings are not the results of immaculate inception nor are they
a "commons" where anyone can, for a single modest fee have a claim
in perpetuity for space rights.
Of course some take the tactic of regular fixed fees to cover the
incidentals of ongoing cost recovery and periodic maintinance.
Others work on a time/materials basis.