I don't think it is a lack of compassion at all. But for every pet project there is a massive beaurocratic administration that comes with it. The universal child care benefit was recently (last year) significantly increased  to the detriment of specialised credits - THis is a good thing. Maybe increase UCCB a little more and then leave it at that. The Tax Code is NOT the best method to deal with autism funding.  In fact the reality of life is that many people/children have some sort of disability or lesser issue that affects them. As a society we cannot cover every base 100%. Better to give a reasonable support (UCCB say) and let families apply the funds as they see fit. If it means the 1-2 autistic kids in a class of 30 don't get all the extra support they need, well a line must be drawn somewhere, and what about the other 28 kids?
 Its like allrgens, Quebec recently realised it is IMPOSSIBLE to be 100% allergen free, the responsibility lies with the family or idividual to take care.