@Orf1abc
Hundreds of thousands of people signed up to volunteer in March/ April, but when it came to actually doing anything, only a small number stepped up. This is the same, if you can't be bothered to complete the form, chances are you won't be particularly committed to the role.
This. ^
Loads of people are all mouth and trousers, and the OP sounds like same. Wants the glory of being a volunteer (and no doubt to crow about it,) but can't be arsed to even fill in the form.
It's a bit like when something (bad) happens in your life, and people say 'if there's anything you need just let me know.' But if/when you DO ask, they umm and ahh, and make excuses to not help.
My (widowed) friend in her late 60s, was moving house several years ago, and a man she knew (an old colleague in his mid 40s,) said 3 or 4 times, 'when you get your moving date, let me know.' He worked in a factory and said he will get a bunch of boxes from work, and help her pack, and also help her move house, (in the van he had.)
So she took him on his word, and on 4th May 2018, she got her date for moving... 18th May 2018, (just 2 weeks notice.) She rang him, and asked if could get the boxes, and come help her.
He said he was off work for the next 2 weeks, and he and his wife were going away for 2 weeks tomorrow, so he wouldn't be able to do it. 'Call 'man with a van' he said cheerily. They'll help! 
This woman I know was gutted. She was 100% depending on him to help her pack, and move house. To add insult to injury, she saw him in one of the city shopping centres 2 days later, so it was clearly a lie that he and his wife had gone away. She also rang his workplace the next day, and asked for him, and they said he isn't in til 2pm. So he wasn't on leave either!
She shouldn't have depended on him so much IMO, but still, this is just an example of how many people are all talk...
As has been said, re; the OP. Of COURSE the people looking for volunteers have to check people thoroughly. Just as if it's a paid role. Why wouldn't they?