The reason for having airport security but not having comprehensive border security can be attributed to a variety of factors.

One reason is that airports are considered high-profile targets for terrorist attacks, given the high volume of people passing through them on a daily basis. In contrast, border security involves monitoring vast and often remote stretches of land and water, making it more challenging to enforce.

Another reason is that airports are under the jurisdiction of the federal government and fall under the responsibility of the Transportation Security Administration (TSA). This centralized authority allows for more standardized and consistent security measures across airports.

However, border security falls under a complex web of federal, state, and local agencies, making it more difficult to coordinate and enforce uniform security measures. Additionally, the sheer size and diversity of the U.S. borders present significant challenges to achieving comprehensive security.

There are also political and economic considerations that play a role in the prioritization of airport security over border security. The economic impact of a terrorist attack at a major airport can be significant, affecting air travel, tourism, and the economy as a whole. As a result, there is often more political will and resources allocated to ensuring the security of airports.

Overall, the decision to prioritize airport security over border security is a complex one that involves considerations of risk, resources, and political and economic factors. However, it is important to recognize the need for comprehensive security measures at both airports and borders to effectively protect the country from potential threats.