Double standards

So here we are again having another argument over double standards.  The way he treats his son and the things that are acceptable for him to do vs. The way he treats my kids and expects them to behave. I really shouldn't even say "my kids" since he is like a stepfather to them.

It's OK for his son to sleep until 2pm, not get up to let the dog out so the dog crapped! on the floor. But, it's not OK for my girls to sleep past 10, when they stayed up laughing and talking (and rearranging their room).

Soda as much as he wants vs. The girls get one per day.

He can use the living room TV all day for movies or video games vs. Girls being told to turn their music down or put in headphones, or watch a movie in their room.

No responsibilities vs. Daily responsibilities.

Allowed to eat food in his room vs. The girls getting in trouble for having food in their room.

The list could go on and on......
I don't appreciate that he feels he can set boundaries and consequences for the girls, when he chooses not to do it for his son. The girls have hurt feelings and feel betrayed.  As do I since I have little to no say in what happens in OUR home, while he's here. His 16 yr old  throws tantrums to get his own way.......and it works!!
WTF?!!!!!!

I'm just venting......