Are you comparing prices to Thailand or USA?
Jakarta is more expensive than Bangkok for food, both in restaurants and unprocessed. I saw an Indonesian from Jakarta in the restaurant industry get angry about it this year when comparing prices. Thailand has a higher wage there but slightly lower average food prices. Thailand has a development level that both lets there be better competition and more efficiency. Indonesia is very protectionist with higher tariffs and quotas on food import. At first this was to get rid of the Dutch after colonialism, then it was to protect domestic production and distribution. Thailand developed a major food production industry. It is a regional powerhouse, importing raw food, processing and packaging it, and exporting it for the world. Some years it can be up to 20% of exports. If you look at many western products in the west, it will say packaged or made in Thailand. There was a viral photo a few years ago of peaches grown in South America, packaged in Thailand and reshipped back to the USA.
Food falls under what is known as the law of one price. Most food is an interchangeable commodity. Freezing/preserving and global shipping is generally a small percentage of the cost. The majority of the difference of price in unprocessed food (grains, meats, vegetables) is tariffs and distribution costs. Since you are from the States, you enjoy some of the lowest food costs compared to average income in the world. Regulation is low, tariffs are low, corruption is low, competition is high, and logistic efficiency of distribution systems are high.
In Jakarta, many of the grocery stores with the quality level of USA supermarkets will have close to the same prices or more expensive. Prepared foods from restaurants will be cheaper, because of the lower labor rates and lower food standards. The other major overhead, real estate, is generally comparable in Jakarta to much of the U.S.A. In my experience, finer restaurants in Jakarta will be 50-75% of the price of the states, without alcohol. Street food is close to the same price as Thailand because it uses many of the lowest quality cheapest ingredients, with cheap labor, and no real estate overhead. Get your typhoid vaccination, it is endemic in Indonesia.