As far as Hotels are concerned, I think they show THEIR price and exclude the additional taxes because all the extra stuff technically isn't their room rate, it's government greed.
However, If you pay the price shown, you're just pissing money away.
Funny you bring hotels up as we stayed overnight for Christmas at a Hilton Double Tree. My wife hit the site 5 different ways using various discount codes before she got a great price. She managed to knock it down from around $139/night to $89/night. Turns out there was a local casino and we got the "Casino Rate" discount which is way better than the others so-called 'deals'.
Always check for a local casino ;)
When we can't get a good rate online we've called the hotel and booked via the desk clerk and gotten significant discounts that way. If you schmooze the clerks, assuming it's not a jerk clerk, they can book under 'deals' we had no clue existed.
Always worth calling the clerk before registering.
Hotel pricing, esp. online, is such a scam.
There have been a few earlier threads about sites that flatly refuse to show you the shipping rate until after you've started placing the order ... and then they wonder why people abandon their carts midway.
How I resolved that on my ecom software back in the day was to ask people for their zip code.
What people don't understand though is sometimes it's the same price for multiple products because your location or an odd sized product can really skew the price.
Then the shopper can select next day, 2-day, or the slow boat from Japan options which changes everything again.
Too many factors in shipping, it's just a PITA.
But there's no excuse for sites not showing shipping except there's a perception that if they can get you to invest all your time filling the cart that you'll complete the sale. Wrong.
All it does is piss people off and make them less likely to be a future customer.