No, it's not standard.
They are free to charge whatever they wish, and it's up to you to decide if you wish to pay it or not.
That being said, I would hope you have the integrity to walk away though because this is pretty absurd. It's nickle-and-diming at it's most glorious and nekkid best.
Just remember, providers are a business too. The best way to get them to change a pattern is to cut into their bottom line: their profit. If a provider sucks (or her policies suck), do not book an appointment. If it hurts her wallet, she'll try to fix the problem.
And to the providers, I'm aware it might take you time to screen someone, but like most businesses, you look like a greedy jackass when you nickle and dime your clients. This is like up-selling, but worse. Think about it from our prospective. It would be pretty absurd if you went to McDonald's and they advertised $5 for a meal... yet you show up to buy it and the cost was really itemized to $8, the ticket breaking down every cost, and the advertised $5 was really their profit...
$5.00 - meal (as advertised!)
$0.20 - gas to ship supplies to store
$0.80 - labor to cook
$0.09 - building heating costs
$0.20 - labor cost to clean restaurant
$0.65 - parking lot snow clearing
... other stuff
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$8.00 due