“The reason is, largely, survivor bias:

Survivor bias refers to the tendency to focus on the examples of something that have survived while ignoring those that did not. In the context of understanding how things were made in the past, survivor bias can lead to a number of mistakes, including:

Overestimating the success rate of historical products or processes: For example, if you only examine the tools or artifacts that have been well-preserved over time, you may think that all tools or artifacts from a certain period were of high quality, when in fact many were not. Assuming that historical products or processes were optimal or efficient: Just because something has survived does not mean it was the best possible version of that thing. For example, an ancient pottery piece which has survived might not be the most technically perfect one and there were other better designs that failed in preservation over time Ignoring important innovations that failed: It is possible that some of the most important innovations in a particular field never made it to the present day because they were unsuccessful or didn't gain enough traction. By only looking at the products or processes that have survived, we can easily overlook these innovations and fail to understand the full range of ideas and experimentation that took place in the past. Failing to appreciate the role of luck in the survival of certain things: Sometimes, the survival of a particular product or process is simply a matter of luck. For example, a ship that sank in a calm sea and was quickly discovered by treasure hunters will be better preserved than one that sank in a stormy sea.”

https://www.quora.com/50-years-ago-it-seemed-like-things-were-made-better-quality-wise-Why?share=1