This parking charge is not really a problem for the savvy, do as I do, get your relative to go up to the departure level drop of area, where there is no charge or walk down the tunnel to the station drop off area.
The cost isnt really an issue, its just the principle. I take great pleasure in avoiding even £1.80.
Complaining to MAPLC will fall on deaf ears, they do after all have to pay the upper management their Xmas bonuses. !