Is a car maker's recall really free?

When I know, for sure, that a recall applies to my car, can I get the recall performed at NO CHARGE, whatsoever, to me? No charge for dealer’s diagnostics, and no charge for other niggling things?

Yes, it’s completely free. However, that doesn’t preclude the dealer from suggesting additional work, legitimate or not.

Yes, recall repairs are supposed to be completely free of charge.

Only as it relates to the recall. It’s free to you. Dealers still gets paid from the car manufacturers.

Yes.

No only are recalls free; retrofits to correct a design flaw are also free. My Ford Granada had a chronic vibration in the driveshaft. This was not a safet issue. Ford’s solution was a counterweight, shaped like a heavy tuning fork bolted to the transmission. It solved the problem, and there was no cost to have it put on.

A recall is free to you. Sometimes car makers start what is called a “campaign”, which could be considered a voluntary PR recall to cure a problem. This campaign is usually limited as to age, mileage, etc. and may also be free.

You did not state the type of vehicle or the problem so do not get recalls, campaigns, and TSBs (Tech. Service Bulletins) mixed up as some often do. And if your vehicle is suffering a vaguely related problem do not automatically assume a recall is going to cure everything wrong with your vehicle.

The supposition is: one thinks that one has a problem covered by a particular recall. One takes ones vehicle to the dealer. Is the dealer required to do a “diagnostic”? And, if the diagnostic DIDN’T prove to be recallable, would I be charged for a “diagnostic”?
A specific instance: neithbor has 1997 Honda Odyssey. Before, sometimes, it stalled, or didn’t start. I filed, and sanded, the ignition switch’s arc pitted contacts. The vehicle was fine for months. Now, the same symptoms have returned. I saw that there is a recall on the ignition switch. Now, what, and how much $$$, if any, to ask the dealer to replace the ignition switch under recall? Or, does the dealer NOT do any “diagnostics” before performing a recall if those particular symptoms are reported?

In the case of the Honda there would be no diagnostics involved. If the customer brought the vehicle in for this recall then that recall would be performed just as stated in the recall bulletin, whether the ignition switch is faulty and acting up or not.
Now if the recall was performed and the customer still had similar problems then any diagnostic after that would be billable; either to the customer or to Honda if the vehicle is still under warranty.

Another scenario could go like this and this was true of my oldest son’s Camaro with the 3.8. GM had a campaign about plug wires on these cars. His was several years out of warranty but GM was replacing or paying for repairs due to plug wires, even if the repair was done by an independent shop.
His car was bucking and jerking, CEL on, etc. The campaign paid for the plug wires but if his car was bucking and jerking for another reason (say fuel filter, MAF sensor, vacuum leak, etc) then GM is not going to pay for any diagnostics or repairs on those items.

In the case of the Honda you mentioned, there should be no diagnostic charge or even any questions asked. It is very important that a customer should specify that only the recall is to be performed. This helps to prevent any confusion because the mechanic out in the shop is too busy to get involved with pulling files to see what has or has not been done.
If the tech gets the Honda won’t start job and nothing about a recall is on the repair order then he would probably assume it’s been done and proceed with other diagnostics that may have nothing to do with the original problem.

If the dealer suggests other work while they have your car, just say no thanks.

The recall is based on VIN. The manufacturer defines a block of VINs and makes the repair on all those cars whether there is a problem or not.