What is it that you feel was made up? I guess there's no certainty that the Harris/Walz campaign contacted the restaurant in advance, but I believe it's what is typically done, so the restaurant can prepare for a crowd that might be double or triple what they'd normally expect.
We certainly know that Vance & the local GOP group did not notify the restaurant, or the manager would've let them know on the phone that they shouldn't come. And we know it was a planned event by the campaign, because they sent out an email blast to the local party members.
I have no experience with a nationwide campaign; I do have some with local events for statewide candidates (governor, US Senate), through a good friend who's one of the more powerful statewide with the Florida GOP. During various campaigns over the last 15 to 20 years, he's frequently hosted meet & greets at a local "family sports pub." I know for certain that he pre-arranges it with the owner of the restaurant - he'd never think of just showing up with 100+ people at a place that barely seats that many.
The Trump ground game this year is horrible. Warning flags are going up all over the country from Republican operatives that the on the ground operations are a disaster. Their get out the vote and voter outreach is basically non existent, and the idea of local GOP officials botching this by simply not making proper arrangements is 100% believable.
The tremendous ground operations of the GWB era have been totally dissipated at this point. And it's 100% Trump's fault, on three counts:
a. He doesn't give a shit or is too dumb to realize he should. His interest is in money directly to him, to his stupid NFTs or coins or trading cards, or donations he can directly use on his legal bills. I don't think you could even begin to impress upon him the need to make sure state operations are are well funded and staffed.
b. The Trump campaign and entire apparatus, at this point, is a grift. At every level. As much as I detest Trump, this wasn't the case in 2016. It was headed this way in 2020, and has fully arrived now. Everyone involved is a grifter...most of the money at the state level GOTV is apparently going to outsourced third party operations instead of tightly managed volunteer networks. I think it's pretty easy to assume those ground game subcontractors are just ways of stealing money.
c. The biggest reason is the "stop the steal" purges of state Republican parties after 2020. Pennsylvania and Arizona were/are some of the worst in fact. State parties blew their budgets on fruitless lawsuits and useless rallies and sham data science consultants etc, leaving them near bankrupt. Any effective, reasonable Republican official that didn't go along with the ceremonial hari kari for the great MAGA father was totally purged. If you follow the actual politics in republican circles, not just the vibes, you've been hearing this for two years...these state level operations are totally broke, decimated, and staffed by the least functional bootlickers. In Georgia, the exception with good Republican leadership, Trump was basically at war with that leadership for years, so it remains to be seen how much of the (impressive) Kemp operation he can even leverage.