I'll chime in as a Leaf driver since end of July 2013 and having had a '13 Leaf w/CHAdeMO (their DC FC standard) from that point until July 2015. I leased that one but bought a used '13 Leaf WITHOUT CHAdeMO to replace it before I returned my 1st Leaf.
First off, Nissan NCTC didn't exist until after I leased my first Leaf, so I was never eligible. And, it's only free for the first 2 years. At the time, some Nissan dealers offered free L2 and DC FCing but it was very YMMV. Some dealers only welcomed those who bought/leased from them, which usually was a dealer near you --> nearly useless.
I have L2 charged my Leaf a few times at a few Nissan dealers (including last year) w/o issue but sometimes had failed attempts (e.g. 1 car blocked by an EV hole (completed but blocking the spot) + other in use), as well.
For most Nissan dealers, the DC FC tended to be behind gates/areas that inaccessible when the dealer's closed. So, when the dealer's closed, you're SOL. I leased my Leaf from Boardwalk Nissan in Redwood City but never once personally used their DC FC as I don't live near there nor would I travel that way much in my Leaf. When it was free, I knew someone who posted on Facebook that she was DC FCing in line and there 5 Leafs behind her! It was a popular travel corridor since they're off of 101.
The Nissan dealer I tended to DC FC at was kinda near home but there was only 1 unit, was free at the time and because it was free, somewhat often had a line.
As for "this would exponentially increase sales leads and customer contact for the dealership." Not really. I never observed this happening when I saw lines.
The closest Chevy dealer to me (not where I bought my Bolt from) has a very low Plugshare score of 2.1. Looks like their DC FC has been broken since September 2018. Keep in mind I'm in Silicon Valley, in the middle of a very strong EV market. (At my work, in our EV + PHEV registry, there are over 500 such vehicles in our registry and over 200 of them are Teslas.)
The dealer I bought my Bolt from has at least 2 or more 24 or 25 kW DC chargers. IIRC, there were signs saying not for public use. They have to use them to charge customer cars. They charged mine on one of them (I sat in my car while it was charging) to get it ready for me. The dealer's nowhere near home, so it's not that likely I'd charge there anyway (if they were open to the public/Chevy/their customers).
As for free or reduced rates, the problem with that is the demand charges could kill the dealer. There was a report at http://www.mynissanleaf.com/viewtopic.php?f=26&t=23794
which is unfortunately very long and complicated. The RMI links are 404 but there's a copy of the report at https://web.archive.org/web/20170412...lysis_2017.pdf
I posted at http://www.mychevysparkev.com/forum/...php?f=7&t=3753
Information provided by Nissan at Plugin 2013 indicates average cost for hardware and installation at dealers for the DC FC is $49K.
At the time, they were installing these units: https://web.archive.org/web/20130112....nissanqc.com/
that are very heavy and not very reliable.
The wall mounted 24 kW units (e.g. https://www.chargepoint.com/products/commercial/cpe100/
) I believe are somewhere past $10K for the unit only and should have lower installation costs due to their lighter weight.
As for "I understand that GM is in the business of selling trucks, not electricity", yes. Unfortunately, GM at the moment doesn't seem to really care about selling much in the way of EVs. Bolt is barely marketed. If you d/l the deliveries PDF file from the left side of https://media.gm.com/media/us/en/gm/...2-gmsales.html
, you'll see that in the US for 1Q 2019, GM sold/leased 665.8K vehicles. Only 4.3K of those were Bolts and the only vehicle that GM current sells/leases in the US that can even be charged via SAE Combo.
Volt (production ended) can't be DC charged. I'm almost positive this was also the case for the ELR (dead) and CT6 PHEV (now also dead). Spark EV could but that DC FC inlet was also optional and Spark EV has been discontinued for awhile, besides being sold in CA and barely anywhere else (Oregon, I think, eventually).
In summary, at least in the US w/the lessons learned from Nissan, it seems like dealers are not really optimal places for DC chargers. And, many of the deployments of CHAdeMO back then were a joke: only 1 DC FC per site. What if there's a line? What if it's down?
At least Tesla did it right w/many charging stalls per location and implemented stuff like idle fees to keep people from blocking spots after they're done.