Accomplishing an e-commerce task

Visit three different websites: an e-commerce site of your choice, a non-profit site, and then a government website. For each site, assume you want to accomplish an e-commerce task: make a purchase, a donation, or perform a government-related task (apply for a job, pay taxes, pay a ticket, etc.). Compare your overall experiences on each site, and note how easy it is to accomplish the tasks:

How do these sites track purchases or donations as users navigate the site?
Do all the sites use secure transmissions for e-commerce (https://)?
What improvements would you recommend for these sites?