Seven of the top private parking firms had a collective turnover of more than £650m and earned more than £50m in profit in the past three years.
The number of tickets issued on private land has risen by 50% in a year to 30,000 a day, which equates to a motorist being penalised every three seconds from April to June.
The firms, which are on course to demand up to £1bn in fines this year, do not own the land where cars are parked but are awarded contracts by retailers, hospitals and landowners to impose charges.
