On the days you need takeout, you tend to really need it. So when the delivery guy shows up late, or not at all, or with cold food, or under some other circumstance that ruins your dinner, it all stinks that much more. The simplest answer is that somebody screwed up, but there's a chance it might not have been the restaurant.
Last month, Eater reported that online food delivery giant Grubhub (which also runs or owns Seamless, AllMenus, and Eat24) has been adding restaurants to its databases without those restaurants' knowledge or permission. When Eater reached out, the company said that it was more or less forced to do so — since it's become industry standard practice (at least when it comes to Postmates and DoorDash), abstaining puts Grubhub at a competitive disadvantage.
Your soggy spring rolls and lukewarm penne plates are likely casualties of third parties, from the ordering system to the delivery contractor. "If things go wrong, the restaurant has to deal with complaints about cold food or slow orders, when it may have explicitly not offered delivery for those same reasons," writes Eater's Jaya Saxena. Restaurants who haven't agreed to appear in Grubhub's database (or, as the company calls them, "non-partnered inventory") can reach out to be removed, but it's extra work that no one on any side wants to take on.
In the meantime, it may be inconvenient or abnormal, but the best way to make sure you're both following a restaurant's policy and giving that restaurant as much profit as possible is still calling them up to place an order or using their own individual online portal.