Once upon a time parishes offered one or two daily Masses, both at times when those in full-time employment could attend.
There have been priests who managed to offer a 6am Mass every day over a long period, even when well past retirement age. No longer. It is not easy to find a parish today offering Mass at a time workers can get to. There are parishes which offer Mass at odd times during the week. Also parishes where the priest takes a day off. And even parishes where priests limit themselves to one or two or even no weekday Mass at all.
Does a priest work so hard that he is unable to find half an hour for Mass every day? In those places where workers go to daily Mass, why is it possible for workers but not for priests, who volunteered for the job of saying Mass?
The Church doesn't think daily Mass is too onerous.
Can. 904 Remembering always that in the mystery of the eucharistic sacrifice the work of redemption is exercised continually, priests are to celebrate frequently; indeed, daily celebration is recommended earnestly since, even if the faithful cannot be present, it is the act of Christ and the Church in which priests fulfil their principal function.
Daily celebration is recommended earnestly. Is the Church being less than reasonable, expecting priests to give 30 minutes of their time to God each day?
In fact, the Church is saying that if a priest has a reasonable excuse (illness, exhaustion etc), then he need not say Mass. The other side of this is that if he does not have a reasonable excuse (ie he just doesn't feel like celebrating, or he wants to watch a football game), it would appear that daily celebration is a requirement rather than an option.
Does the Mass save souls? And if it does, are souls lost which might be saved if Mass was celebrated?
The bottom line here is that if a priest fails to celebrate Mass for no good reason, is he not responsible for the loss of any souls which otherwise might have been saved?