Due to the lack of an adequate privacy law or protection at the federal level in the United States, European privacy regulations generally prohibit the exporting or sharing of PII from Europe with the United States.
Participation in the Safe Harbor program is voluntary on behalf of an organization, but it does require them to conform to specific requirements and policies that mirror those from the EU.
Thus, organizations can fulfill requirements for data sharing and export and possibly serve customers in the EU.

Explanation
When leasing space in a data center versus utilizing cloud services, a customer has a much greater control over its systems and services, from both the hardware/software perspective and the operational management perspective. Costs, regulations, and security are all prime considerations regardless of the hosting type selected. Although regulations will be the same in either hosting solution, in most instances, costs and security will be greater factors with leased space.

Within a SaaS implementation, the cloud customer licenses the use of the software from the cloud provider because SaaS delivers a fully functional application to the customer. With SaaS, the cloud provider is responsible for the entire software application and any necessary infrastructure to develop, run, and maintain it.
The purchasing, development, and maintenance are fully the responsibility of the cloud provider.

Signed into law and effective starting on September 1, 2015, Russian Law 526-FZ establishes that any collecting, storing, or processing of personal information or data on Russian citizens must be done from systems and databases that are physically located with the Russian Federation.