So she buys an aircraft that can only deliver about 110 tonnes a day like the NSW 737. That is the 737s historic performance.
Using Morton Bay (Greece and other nations use the Med) a Canadair doing just 6 rotations (drops) per hour (the average in North America) with 6 tonnes per drop for 12+ hours delivers some 400+ tonnes of water/foam on a normal day.
The record for drops per day done by a single Canadair and 2 crews alternating in sorties was 207 drops, hence delivering over 1200 tonnes on that day, Italy July 8th, 2018.
And before you say but Australian fires are different because Aus is hotter and dryer look at Spain. Eucalyptus in the bad fire areas around Pamplona and the same average annual temperatures as the Blue Mountains. The Blue Mountains have 40% MORE rain than Pamplona so the fire risk is worse in Spain.
Spain has 21 Canadairs and uses them intelligently - they, like other countries, use them the moment a fire starts and hit it hard Go to youtube and search for Canadair CL-415 water bombers, and idiots with boats and you will see they are spaced 20 seconds apart - 18 tonnes an hour and 15,120 tonnes per 14 hour day sure beats the hell out of 110 tonnes a day with two hours between drops (so that the fire can dry out the drop zone and start it burning again) and waiting for the fire to be out of control before bringing in the heavy hitters..