Rivals only researching a few techs?

Hi, I bought the game a week or two ago from GOG and am really enjoying it so far. One thing about it seems a bit off to me though, and I’m not sure whether it’s a bug in my copy, or me having the wrong expectations.

I’ve played the small factory mission in sandbox mode up to day 20, and the mega factory mission in sandbox mode up to day 9, and in both cases, my rivals are only researching the cheapest features (the ones which need 750 research points). After a certain point (quite early on!) they just keep repeating those features, and it doesn’t even affect how common those features are. In-car music ends up common for all price levels, heaters end up rare for budget models and common for everything else, keyless entry ends up rare for expensive cars and common for luxury ones, etc. I keep getting notifications that these cheap techs are being researched by rivals again and again, but it never affects the rarity levels anymore, and they never research any techs that are more than 750 points.

Is it meant to be like this? It gets a bit boring, and I was under the impression that rivals would research all the features eventually. Is it because I’m only playing in sandbox mode? (note: sandbox, not freeplay!) Have I just not been playing for long enough? In the small factory mission, I’ve already researched every feature, and meanwhile my rivals are just researching basic stuff like electric windows over and over again and getting nowhere.

Oh, another potential cause for this issue - I’ve not really bothered trying to expand my production much yet; in both games, I’ve focused on reducing bottlenecks in a production line that is fed by a single ‘fit front axle’ module, meaning my production rate is down in the low 20s. Maybe rivals are programmed to only start researching more advanced tech once you expand your production a greater level? Seems odd if that’s the case though.