People tend to underestimate how fast technological progress can happen

It depends on the technology and the progress.

If you look at a history of technological progress, there's a very strong case to be made for it having peaked in the period 1880 - 1930 or thereabouts. At the beginning of this period, electric lighting, automobiles, airplanes, radio, refrigeration, indoor plumbing (outside very few exceptions), central heating (indoor plumbing is far more tenable when your mains and sewage pipes don't burst from freezing), steelmaking, widespread photography, cinema, and the beginnings of petrochemistry and pharmaceuticals.

The 1930s-1950s saw petrochemicals, synthetic fibers, plastics, and pharmaceuticals. Radio, television, and microwaves. Solid-state electronics and computers. Aircraft and air transport.

Since 1975 has been a rather different climate. The period from 1933 to 1973 saw huge social and technological tranformations, enough that a person transported from one to the other would need significant acclimatization. From 1973 to the present there've been some changes in hairstyles and clothing, cars have gotten smaller and generally more efficient, airplane tickets cheaper (thanks largely to deregulation) but flights slower, and some technologies first pioneered in the late 1960s (WIMP computer interfaces, Unix, ARPANET (now the Internet), TCP/IP, and microprocessors), have become vastly cheaper and more powerful. _What you can do_ with the technologies hasn't changed so much as who can afford to do them (damned near everybody).

Robert Ayres, "Technological Transformations and Log Waves" describes much of this (in particular it lays out five technological transformations).

http://webarchive.iiasa.ac.at/Admin/PUB/Documents/RR-89-001....

I've discussed this at more length on G+:

https://plus.google.com/104092656004159577193/posts/6sJbXhwj...

What we've seen since the 1960s has been largely confined to increases in computational power and some consequent results of that. In particular, better management of manufacturing and design processes, but all aspects which trace back to Moore's Law. Randall Lee Reetz on G+ frequently iterates over this theme (he's irrascable but technically very solid):

https://plus.google.com/+RandallLeeReetz/posts

In particular, there's a great deal which was predicted or projected starting in the 1950s which hasn't materialized, most of which are hard problems of integration or massive resource utilization. We don't have colonies on the Moon, artificial-gravity space stations (the one assemblage of pressurized cans we do have is the most expensive single structure ever created by humans), orbiting power stations, flying cars, jetpacks, world peace, freedom from hunger, equitable wealth and income distribution (or even educational opportunity), or even highly reliable, privacy-respecting, integrated home management systems. Systems integration is a huge part of any techie's job description, and it's hard.

Regards the specific case of high-speed arial package delivery, outside a limited range and weight limit, I doubt this will be very widespread. Air freight exists, but it's limited to a minuscule fraction of all freight delivery. The EU saw 14.5 million tonnes of air freight in 2011. That compares with 3.6 billion tonnes of sea freight. Road/rail aren't clearly indicated below but are also substantial.

http://epp.eurostat.ec.europa.eu/statistics_explained/index....

For the US, air freight is 0.1% of total weight, 0.3% of ton meils, but 7.4% of value (high-value and time-sensitive goods tend to move by air).

http://www.rita.dot.gov/bts/programs/freight_transportation/...

Truck value is 63.7%, weight is 58.2%, and ton-miles is 32.1% (shorter-haul, moderate-value goods). http://www.rita.dot.gov/bts/programs/freight_transportation/...

Rail is 3.7% of value, 12.0% of weight, and 27.8% of ton-miles (largely low-value bulk goods). http://www.rita.dot.gov/bts/programs/freight_transportation/...

Water is 8.3% of value, 14.8% of weight, and 15.3% of ton-miles (domestic). It's over 75% of all international freight by weight.