But I noticed that none of the priests seems to have a server and this is a problem. It used to be considered quite a grave thing to celebrate a solitary Mass (as opposed to a "private Mass" where a server would be there.) For the traditional Roman Rite, a server is really essential to answer the responses, say the confiteor, and minister the ablutions. Since Vatican II, it has become more common for priests to celebrate Mass without a server or - which is essentially the same - for a group of priests to concelebrate without any of them acting as a minister and answering the responses.
Canon Law encourages priests to say Mass every day:
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 fulfill their principal function.It is specified that normally there should be someone else present apart from the priest:
Can. 906 Except for a just and reasonable cause, a priest is not to celebrate the eucharistic sacrifice without the participation of at least some member of the faithful.I would say that the priest's desire to celebrate a daily Mass would be a just and reasonable cause for him to celebrate even without the presence of a server. So I am not criticising the FSSP priests for celebrating this way.
Nevertheless, the tradition of the Church is that there should be at least a server present. This is difficult to arrange nowadays because men feel less of an obligation to be around to serve private Masses early in the morning. I imagine that at Lourdes or Lisieux, for example, men would have been prepared to serve a Mass when a priest came out of the sacristy on their own.
Another solution to the problem was for priests to "double up". If two priests were on holiday together, they would say Mass in turn, serving each other. The Mass of one's friend could be either the preparation or the thanksgiving for one's own Mass.
It seems to me that this is one of the elements of tradition that is slightly awkward, and a little difficult to arrange - but important for the recovery of the real living tradition of the Church.