How do you deal with a mom who wants everything 50-50 between two siblings but only gives one control. Who has taken advantage of this?

oy do I know exactly what u mean-
except I am the one who lives near mom,he is 5 hours away,and comes 1 time a mo for aout 3 hours.
but he has the POA-iwe used to share it,
but she changed it when we had a big falling out-and
that was when it was changed.
it sucks

Well if she wants everything to be 50/50 and only one has financial control, then things aren't 50/50. She can change this easily. Take her to a lawyer and have her make a new Power of Attorny with both of your names on it. She will sign it and have it notarized. This nullifies the previous one. Neither you nor your sister can do anything without the other's approval. Everything she has can have more than one person's name on it. This may cause war but it will make things even. At least she wants things to be fair. My Mom has everything in my brother's name and when I questioned this he told me things would not be 50/50 bbecause that is the way Mom wants it. That's OK with me, he can take care of her too. haaaaaa

I get why your mother wants to keep it 50/50. My husband's whole family was raised that way, so it's normal to me. Your mother doesn't want to show ANY favoritism between her kids. She wants to keep the peace, so it's her way of doing that. My only suggestion would be to try to separate the equality of money to be left in the event of her death (the 50/50 part) and what is going on NOW. Right NOW things to be handled differently, then tell her your concerns about the mismanagement of funds. Acknowledge the fact that you appreciate that she wants things fair between the kids though.
If her thinking is anything like my husbands family is, then that's what I would do. Good luck.