What is a good enough reason to not allow someone to watch your child?

My mother and I have very different parenting views and things that we think are acceptable and because of this my husband and I have agreed to not allow her to watch our kids until they are much older and have a good understanding of our expectations even when we aren’t around. My mother feels that this is unfair and makes me feel guilty all the time about it, saying that she doesn’t get enough time with her grandkids and stuff even though she sees them with us 1 to 2 times a month. So my mother has young kids now because she had my siblings years after me so our kids are all close to the same age. This complicates thing because she is still parenting, instead of just being a grandma. My younger siblings have a lot of freedom. They are 4 and 6 and even since the youngest one was 2 they have been allowed outside to play in the back yard by themselves, they go in and out of the house as they please. She also doesn’t stop them from doing dangerous things, she’ll ask once and then if they don’t listen she just gives up and allows them to keep doing whatever the unsafe thing is that they are refusing to listen about. Her kids have gotten hurt because of this. She feels they will learn from their mistakes, I feel that this is irresponsible and as a parent there are situations that you cannot allow to happen whether that makes you the bad guy in that moment or not. My husband and I parent a lot differently. We are consistent with our kids and their boundaries. They are not allowed outside by themselves (oldest is 3). When we were at her house recently my kid went to her and asked to go outside. My husband and I l were in the house visiting with other people and my mother brought our kid outside. We figured that she was bringing her out to spend time with her and was going to watch her and minutes later she came back inside so my husband went to the backyard and she had left her all by herself. I feel like she’s so ditsy all the time and just doesn’t assess safe situations properly to ensure they are safe and that makes me not trust her. She is also a yeller. One of those parents that instead of setting consistent boundaries with her kids and not allowing them to push her, she instead thinks it’s better to allow them to do whatever they want and when she gets overwhelmed just yells. I honestly find it so annoying spending time around her because she is so ridiculous with my younger siblings. Would you let someone like this watch your kids? Am I wrong for not allowing it?