Tiger Airway not seating minor child with parent

I am flying from Taipei to Tokyo and first time using Tiger Airway. I know it's a budget airline. My kid is 5 year old. I have never had to pay extra fee just to be seated to her. Obviously, budget airline is different. But with AirAsia in the past many years ago when I flew it, they allowed free seating with minor when contacting customer service.

I called Tiger Airway today to request seating next to my 5 year old. They told me that they can't do that unless I pay the extra seating selection fee. I asked if I don't pay, then my 5 year old have to sit by herself? They said unfortunately we have no choice without paying the fee. Pretty upset about it. Not just because of the money, but in principle, not allowing the parent to sit with the minor unless they get extra money seems wrong.

I can take the strict baggage rules and the bare essentials on budget airlines, but it feels wrong to bend the knee and pay them to allow my child to sit with me. Does anyone have success requesting seating with their minors without paying Tiger Airway? Or I just have to accept this even though it doesn't feel right to me?