What does a host couple do for a wedding?

a fairly long time ago, almost every wedding was planned and paid for by the bride's parents… and so wedding invitations generally read something like "mr… and mrs… smith request the pleasure of the company of ……… to celebrate the marriage of their daughter, miss (the bride) to (the groom), son of ___, on saturday &c…"

fast forward to modern times it is no longer a given that a wedding is planned and paid for by the bride's parents… and it's no ones business who pays for what… so a modern wedding invitation is issued in the passive voice — no host is named… "the pleasure of the company of ……… is requested at a small dance (or whatever) to celebrate the marriage of (the bride), daughter of ___ to (the groom), son of ___ on saturday &c…

it is assumed that the couple and all parents are hosts… it would not be polite to interest oneself in who pays for what so pleease don't bother with wondering what it means to see this or that "host couple" listed on a wedding invitation…

My 83 year old dad keeps spending my inheritance money on prostitutes?

You are old enough to make your own money if your father is 83.
His money isn't your money, and nowhere in your post do you express any concern for him, just his money.
From where I sit, you don't deserve to inherit it, much less dictate how he can spend it.
It ISN'T your inheritance, it is money owned by another adult, and he can spend it on whatever he likes, down to the last penny.

Why do white people find it so incredibly hard to not be racist?

I feel even more confident about this answer than I would have before the election. Racism is taught, period. It begins in the home and finishes with associating with people who think just as you do because they too heard it every night around the dining room table. Sometimes we rise above it – college helps, as well as seeing the reality of life when away from those early influences. But many whites who are poor and struggling need something to blame besides themselves, so looking down on those of color makes them feel superior about at least one thing in their lives.

There are so many reasons, and this problem is reaching critical mass.