With Walmart and HEB curbside in the Austin area it's been very common for subs/out of stocks.
Going into the HEB over the last week has shown rapidly fluctuating stocks in many items. For example diet drinks of almost any kind were sparse in the store. Meat and cheese was well stocked, but bread was half stocked. Then I may go another time and the items that are missing are in stock and something new is missing. Very hit and miss.
a) curbside services charge a nifty premium, and stores revenue share with them. I'd be surprised if that doesn't lead to prioritization.
b) this is demand usually known well in advance, which helps the stores deal with planning.
c) In many stores, it's strictly a shelving issue. If the curbside service has in-store pickers, there's a chance they can skip shelving and the need for shelving staff.
d) The curbside delivery workforce is a bit more elastic, so Covid shortages don't necessarily manifest the same way.
c
B. I think that is giving them too much credit, I normally use Kroger, and even if I place my order a few days in advance I can edit it (and normally do) up to midnight before my pickup day.
C. this is likely true.
e) Curbside usually doesn't offer everything in store. It only offers the most popular or plentiful items.
For example, if I go to my local mega-chain supermarket, I can choose from six or eight different brands of white bread. If I do the order online, there's only three.
But I have not seen any major changes in my curbside pickup order, no major out of stocks, no major substitution.