the transported unit had the colision volume rarely possible to show using alt-V in 0.89 and at 0.91 nothing changed the unit can collide and mess without damages despit true at the :
allowCrushingAlliedUnits=true, --Default: false New in version 85.0
--Can allied ground units crush each other during collisions?
--Units still have to be explicitly set as crushable using the crushable parameter of Spring.SetUnitBlocking.
allowUnitCollisionDamage=true, --Default: false New in version 85.0
--Do unit-unit (skidding) collisions cause damage?
& never a transported unit with 1hp died before transporter with 20000hp
targetableTransportedUnits=true, --Default: false New in version 89.0
--Can transported units be targeted by weapons? true allows both manual and automatic targeting.