Finding jobs in city A is not as simple as it is in city B
这句话应该很好理解吧
因为it可以指代动名词及其词组,这里指代finding jobs
您说的that（指示代词）用于指代事物的具体用法如下：
1 that 指代单数名词,包括可数名词单数,和不可数名词,其复数为those,指代可数名词复数
2 that 和 those 指代的内容一般有限定成分,最常见的就是在被指代的事物或人前加定冠词the
综合1和 2的用法,有如下例句
1.The son of yours is smarter than that of his.
2 The students in Class 3 are much more talkative than those in Class 4
注意：如果可数单数名词前面是（不定冠词）a或an时,我们用one指代
如A kid from a rich family may not be as strong in mind as one（is） from a poor family.
那么我们知道that,指代是事物、人或事情,而且被指代的成分要有限定成分修饰,所以我们可以把楼主的例句改成
Job finding in city A is not as simple as that （is） in city B.（这里that 指代的是job finding这件事,期中finding被job限定,强调是找工作,而不是找别的什么事物）
=The finding of jobs in city A is not as simple as that （is） in city B.
希望能帮到您