It reminds me of my previous company, also a car company. During the Dakar Rally they had an 8MB jpeg as the header of their sale website. It took one week and a message sent through a "Contact us" page (public) to get them to reduce it to 700 KB. I suppose it happens because the web devs never tested the website with a realistic internet connection. Everything loads fast when the server room is less than a km away with gigabit bandwidth. It's either bad project management if they forgot to test correctly/change placeholders or as you said lack of knowledge.