Actually, under Queen Mary Tudor there were (sadly) about 250 Protestants who were killed.
Under Elizabeth I, there were probably closer to 800 killed throughout England, Ireland, and Wales. Of course, Elizabeth’s reign was longer.
I admire Elizabeth as a Queen who certainly knew how to pick her conselors. Mary Queen of Scots, OTOH, was handicapped by having a very poor ‘pool’ from which to chose, as well as not being particularly suited to queenship on many counts.
Traitors? Yes, that was an early example of how words can be twisted. Few if any of those killed by Elizabeth were ‘traitors’; most expressed approbation of her queenship, and were perfectly ready to take the Oath to her as queen but not as ‘head of the church’. The so-called ‘Catholic’ plots of Norfolk, and Babbington, were mostly drummed up by Walsingham, who used counteragents, faked ciphers, and faked correspondance in an effort to get Elizabeth to stamp out Catholics. Why? Because Walsingham, Cecil, et. al. liked power. If by any chance there was a revolution/reformation/tolerance so that Catholics would be able to function fully as citizens, the ‘balance of power’ could conceivably shift. Cecil had barely made it through Mary’s reign even though he turned his coat very quickly, was assiduous in attending Masses under her, and flew very low. Considering that only Elizabeth’s life lay between him and the ‘next’ ruler–who would have been Catholic–either Mary QOS, or possibly Philip of Spain had he pressed for war, or even Catherine Grey, Elizabeth’s heiress presumptive until she managed to louse up by secretly marrying–and losing the documentation and witnesses–and producing thus ‘illegitimate’ children–or Norfolk himself who was one of the premier male relatives–Cecil would have been quite anxious to see Elizabeth do as much as possible to get rid of as many Catholics as possible.
As for the pope meddling–well, England HAD been made a fief of Rome way back in the 13th century under King John, you know.

Also, at least half of England’s population–and probably closer to 2/3 when you factor in Ireland–was Catholic at the start of Elizabeth’s reign. And saw the Pope as head of the church. Weren’t they entitled to know what the Vicar of Christ had to say? Didn’t the Pope have a right to instruct his flock, wherever they might liv?