Right, but the customer doesn't have TomTom over a barrel either. If producing maps for older devices doesn't net a lot of customers, they either charge quite a bit or don't bother.
The device you link wouldn't net updated maps of Australia. Looks like world map devices are closer to $400.
And the customer's alternatives include "just use year-old maps" and "use google maps" so it's not like tomtom have the customer over a barrel here.
[1] https://www.amazon.com.au/Updates-Lifetime-Smartphone-Messag...