This is really the problem with everything Walmart has done wrt eCommerce/online pickup IMO - It's like all the pieces are there, but they can't bring them all together.
I've hit their website from Google looking for an item, and the lead time to ship is 2+ weeks and it's highlighted that it's sourced from a partner.
Putting aside the obvious - it's just a worse deal. For most items, they're competing with 1-2 days, a product page packed with verified reviews to help decision making, a company with top notch customer support/return policies and the price is usually the same or cheaper, there's other issues at play too.
It's subtle psychological cues. First, the way they highlight that it's from their partner almost makes it seem like they're doing dropshipping, they don't actually know if it's in stock and I can order and they will put a hold on my credit card. Maybe I'll get it in 2 weeks. Maybe a month. Maybe the order will eventually be cancelled or I will go through a nightmare dealing with their support or having to do a chargeback.
I'm not going through all of that stuff in my head, it's just my mind in the background doing pattern matching with other bad experiences I've had shopping online.
I understand it takes time and truckloads of money to get something even close to what Amazon has, but it also requires good leadership at the executive level.
The one area that Walmart could absolutely crush Amazon in would be picking up your order online, same day. Walmart should be able to leverage all their experience with brick and mortar to do this.
Instead, they're flagging behind Target. Their solution is pretty middle of the road, all the big retailers have something similar.
Amazon bought Whole Foods, so they have a footprint, just like Walmart has an online store. Based on how these companies have executed which do you think happens first? Amazon nails in person pickup or Walmart nails online shopping.