I find it odd too. I did hear on a news item on the TV the other day, that you can get 25 times more stock in an articulated lorry, than you can get into a van, but it only costs 6 times more to take that lorry to Ukraine. Something like that. Basically, you are much better off finding somewhere that is taking in supplies for Ukraine and going with huge lorries. You can get a LOT more supplies there a lot quicker, and for less money!
As for the 'van-takers!' I hate to say this, but it does smack of attention seeking, virtue-signalling, and as someone said 'having a story to tell.' Maybe they want to feel part of something, and want to feel useful, but it IS coming across a bit attention seeking, and more about THEM than the Ukrainians. Nice for them to have a 2-week jolly across half a dozen countries at other peoples expense too! It's like these uni grads on their 'gap yar' who expect people to fund their trip around 10 African and Asian countries! 
Martin Roberts from Homes Under The Hammer is one such person. His face was on TV all day yesterday - and the day before with his van, and all the goodies he is taking across to Ukraine and Poland. And the people interviewing him were all 'oh aren't you an ANGEL?' and 'you are SUCH a good person 'and 'if only OTHER people were so KIND... and did the same as you.'
Well 'Lorraine' (SHE was one of them! Lorraine Kelly!) Guess what? Some people have actual JOBS, and FAMILIES, and COMMITMENTS, like vulnerable family members to care for, and pets, as well as their children! And not everyone has a fucking VAN, or the means and the funds to do what Martin Roberts - and other virtue signalling attention-seekers are doing!
Martin Roberts actually, has been slated on social media by some people, for his publicity-seeking 'look how KIND I am' shenanigans! Especially as he filmed himself CRYING at the plight of the Ukrainians! #attentionseeker and #MeMeMe some people put!
I sound like a grouch. IDGAF!
As has been said, it's MUCH better to give money anyway!