You are still left with the same scenario as if the store listed the individual shipping price on the front page
Google isn't going to know what other items you _might_ add to show you a "real" shipping cost
There’s a lot of legitimate case were showing shipping price upfront is just not doable or valuable to the customer.
BTW there are a surprising amount of shops for specialized goods that won’t even list the final price at the end. The customer places an order, and they update it with a finalized price after a human looks at the content, and from there the customer is free to pay the transaction or give up the order.
It's the T (taxes) part that may be still a tipping point these days, but it's just between vendor and your state,
In my experience, the most fluctuations were on international shipping by small vendors. Lego bricks for instance, where it makes a big difference if you request 5 small pieces that weight 20g total and can wait 3 months, or if it's 500+g in a middle sized box and you want it in 2 days.
Even with average indication on what to expect, depending on the combination you are requesting the vendor might use a different carrier, different shipping method and so on. They could make it more simple with a range of arbitrary standard fees, but then it costs a lot more to the customer, putting the vendor at a disadvantage price wise. In particular people have visceral reactions to overly high shipping prices.
Add items to card, check the total price and then decide whether to buy it(i remember trying to order some stuff form one japanese plamo store - and it didn't provide exact prices before checkout. I went through the process, but even the cheapest option for delivery was way too high - as 2x price of the whole order)