You think small businesses are doing badly right now - wait until the USPS closes and every home business comes to a complete halt.
I say this as a entrepreneur that ran an extremely successful & lucrative business out of my home that depended on the USPS to both deliver my products but also to seemlessly allow my to do so without leaving my home and at the most advantage cost in the market.
Other options are only more cost effective for businesses that have significant volume. Folks running T-shirt, crafting, Etsy type businesses depend on the USPS to even have a chance at making any profit.
I also say this as someone who has traveled extensively including living abroad for several years. Getting mail across a country this size in a generally timely, low cost & accurate manner is no small feat.