The reason is that there is profit to be made by inefficiency.
When rail is used, the people who profit are;
- the sender
- the recipient
- the railway company
- the train drivers
- the community.
When Trucks are used, the people who profit are;
- the petrochemical companies
- politicians who receive contributions from Petrochemical companies
- vehicle manufacturers
- vehicle maintenance providers
- vehicle parts providers
- the trucking company
- politicians who receive contributions from trucking magnates.
- road maintenance and construction companies.
- politicians who receive contributions from the construction industry.
These are all at the expense of;
- the sender
- the recipient
- the community
- other road users
- emergency services
- the poor truck driver who is high-as-kite on amphetamine in order to meet his outrageous deadline.

ANCAP guidelines are pushing for larger and larger vehicles.
Crumple Zones, and pedestrian protection add significantly to the size and weight of a vehicles, and negatively impact driver awareness.
Driver Assistance is OK to provide an extra level of protection, but result in complacency.
A compact vehicle with good visibility and visceral road awareness will be less destructive on the roads than an oversized SUV with a driver ignoring all the ADAS technology blithely unaware of their surroundings.
That said, a compact vehicle with unobtrusive ADAS would be even safer.