Most every government (whether or not it is a democracy, and whether or not it actually has serious and continuing problems with terrorism) latches on to terrorism as an excuse (though rarely the only excuse) to throw off legal (and/or traditional, depending on the nature of the--note the small "c"--constitution) constraints on the powers and activities of government.

> The reason is that terrorism is optimized to scare voters.

True.

> And politicians are scared of hysterical voters, they need to fix that.

Less true; politicians have a often want hysterical voters -- hysterical voters that can have a prepackaged solution (even if the conception has little to do with the problem that has made the voters hysterical) are very popular with politicians, because its how they get approval to do things that they want to do that would, aside from the hysteria, never be acceptable. Note how many of the measures adopted in the US in response to terrorism were things which had either been tried previously under other pretexts (most recently, in many cases, in the Drug War) -- either proposed as legislation and failed, attempted without legislation but ruled illegal without supporting legislation, or had legislation passed but ruled unconstitutional when adopted for domestic law enforcement purposes.