If the seeds are retail packages purchased from stores, I wouldn't be surprised to find a low germination rate - regardless of what might be printed on the packet. Once those seeds leave the packing plant, they are subject to unknown conditions during shipping, handling by people who know nothing about seeds, and stored or displayed in hot or humid locations. Before I began seed saving, it was not uncommon to have a lot of 'duds', and for bean seeds to deteriorate after only 2-3 years.
Even mail-order seeds can have problems. Sometimes (too often IMO) I found out after the fact that I was not alone, and the company had known issues with germination. And if expecting seeds in the mail in late Spring, I try to watch for the delivery, since my black mailbox can get very hot on cloudless days.
And of course, when getting bad germination results, it could be due to weather, pests, diseases, or improper planting. Some seeds are very sensitive to soil temperature, and will either rot or remain dormant outside their preferred soil temperature.
I suddenly began having serious germination issues with direct-seeded beans and soybeans, after years of great results. It turns out that the seed corn fly finally found my rural garden, to the degree that there were some total failures.

The seeds themselves, once started as transplants, proved to be good. Apparently seed age does play a role in susceptibility to the fly maggots, since the varieties which were newer & came up more rapidly were least affected.